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BEGIN:VEVENT
SUMMARY:Tomas Roubicek (Math. Inst. Charles University)
DTSTART;VALUE=DATE-TIME:20201012T134000Z
DTEND;VALUE=DATE-TIME:20201012T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/1
DESCRIPTION:Title: The old Stefan problem in a new mechanical context\nby Tomas Roubi
cek (Math. Inst. Charles University) as part of Nečas Seminar on Continuu
m Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martin Doskar (Czech Technical University)
DTSTART;VALUE=DATE-TIME:20201019T134000Z
DTEND;VALUE=DATE-TIME:20201019T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/2
DESCRIPTION:Title: Micromorphic model for mechanical metamaterials\nby Martin Doskar
(Czech Technical University) as part of Nečas Seminar on Continuum Mechan
ics\n\n\nAbstract\nMetamaterials\, with their internal composition careful
ly designed to feature exotic and often counterintuitive properties such a
s cloaking or band gaps\, are the prime example of a pronounced influence
of material’s microstructure on its macroscopic response. Regarding mech
anical responses\, metamaterials have already delivered high stiffness-to-
weight ratio\, negative compressibility\, and tunable auxetic behaviour. T
hese mechanical metamaterials often rely on internal instability mechanism
s that trigger transformation of their periodic microstructure into predef
ined patterns\, which introduces strong kinematic coupling among adjacent
periodic metamaterial cells and leads to significant size and boundary eff
ects. As a result\, the standard first-order computational homogenization
fails to provide an effective model of such metamaterials.\n\nThis talk pr
esents a micromorphic computational homogenization scheme that has been re
cently developed specifically for the instability-driven mechanical metama
terials. The scheme introduces characteristic deformation patterns at micr
oscale\, whose magnitudes are communicated across adjacent macroscopic mat
erial points by scalar modulation fields\, which are added to the standard
continuum formulation at the macroscale and for which an additional micro
morphic-like conservation law emerges at macroscale. Consequently\, the pr
esented scheme captures the above-mentioned size effect and boundary layer
s and accounts for with spatial mixing of multiple patterns. Combined with
the bifurcation analysis\, the scheme also correctly predicts local to gl
obal (i.e. micro vs. macro) buckling transitions.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edoardo Mainini (University of Genoa)
DTSTART;VALUE=DATE-TIME:20201026T144000Z
DTEND;VALUE=DATE-TIME:20201026T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/3
DESCRIPTION:Title: Linearization of finite elasticity\nby Edoardo Mainini (University
of Genoa) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\
nWe show some new results about the linearization of finite elasticity by
means of Gamma-convergence\, including the incompressible case and pure tr
action problems.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Bresciani (TU Vienna)
DTSTART;VALUE=DATE-TIME:20201102T144000Z
DTEND;VALUE=DATE-TIME:20201102T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/4
DESCRIPTION:Title: Linearized von Kármán theory for incompressible magnetoelastic plate
s\nby Marco Bresciani (TU Vienna) as part of Nečas Seminar on Continu
um Mechanics\n\n\nAbstract\nWe study the asymptotic behavior\, in the sens
e of Gamma-convergence\, of a thin incompressible magnetoelastic plate\, a
s its thickness goes to zero. We focus on the linearized von Kármán regi
me. The model features a mixed Eulerian-Lagrangian formulation\, as magnet
izations are defined on the deformed configuration.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daya Reddy (University of Cape Town)
DTSTART;VALUE=DATE-TIME:20201221T144000Z
DTEND;VALUE=DATE-TIME:20201221T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/5
DESCRIPTION:Title: Some mathematical aspects of models of strain-gradient plasticity\
nby Daya Reddy (University of Cape Town) as part of Nečas Seminar on Con
tinuum Mechanics\n\n\nAbstract\nStrain-gradient plasticity has become well
established as an approach to modelling seize-dependent phenomena at the
meso- and microscales. This presentation is concerned with a class of mode
ls of strain-gradient plasticity\, which mathematically are formulated as
variational inequalities. Conditions for well-posedness are reviewed\, fol
lowing which attention is given to some aspects of what is referred to as
the dissipative model. Though in a sense a natural extension of convention
al plasticity\, this model possesses some distinctive features\, most part
icularly that the plastic flow relations take a global form. The consequen
ces of this feature are discussed\, for example\, in relation to determini
ng the stage at which incipient plastic behaviour takes place. The present
ation also treats issues relevant to approximations\, such as the converge
nce of predictor-corrector algorithms\, and approximations under condition
s of minimal regularity.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Bravin (BCAM Bilbao)
DTSTART;VALUE=DATE-TIME:20201109T144000Z
DTEND;VALUE=DATE-TIME:20201109T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/6
DESCRIPTION:Title: On some properties for an incompressible\, non-viscous in-out flow in
a 2D domain\nby Marco Bravin (BCAM Bilbao) as part of Nečas Seminar o
n Continuum Mechanics\n\n\nAbstract\nIn this talk I will present some rece
nt results on some properties of an in-out flow\nassociated with a perfect
two dimensional fluid. In particular I present existence of\nsolutions in
different classes of regularity and I will conclude with the study of the
\nasymptotic limit of some shrinking sources and sinks. This work is motiv
ated by a\nquestion left open by Judovic in [2].\nThe system consists of a
n Euler type system in a bounded domain with some holes\nwhere non-homogen
eous boundary conditions are prescribed. I will present how to extend some
classical existence results in this setting and then I will consider the
case\nwhen the holes shrink to points. The boundary conditions lead to the
creation of some\npoint sources and sinks associated with some vortex poi
nts in the limit. Similar type of\nsystems have been already study by Chem
etov and Starovoitov in [1]\, where a different\napproximation approach wa
s considered.\n\nReferences\n\n[1] Chemetov\, N. V.\, Starovoitov\, V. N.
(2002). On a Motion of a Perfect Fluid in a Domain with Sources and Sinks.
Journal of Mathematical Fluid Mechanics\, 4(2)\, 128–144.\n\n[2] Judovi
c\, V. I. (1964). A two-dimensional non-stationary problem on the flow of
an\nideal incompressible fluid through a given region. (Russian) Mat. Sb.
(N.S.) 64 (106)\n562–588\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jacopo Ciambella (Sapienza Università di Roma)
DTSTART;VALUE=DATE-TIME:20201116T144000Z
DTEND;VALUE=DATE-TIME:20201116T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/7
DESCRIPTION:Title: Fibre re-orientation in anisotropic viscoelastic materials\nby Jac
opo Ciambella (Sapienza Università di Roma) as part of Nečas Seminar on
Continuum Mechanics\n\n\nAbstract\nIn this talk\, we will derive a nonline
ar viscoelastic model for fibre-reinforced materials based on the kinemati
c assumption that the deformation gradient can be multiplicatively decompo
sed into viscous and elastic components\, i.e.\, F=Fe Fv. The model is the
rmodynamically consistent and the evolution equation of the viscous deform
ation will be derived by combining suitable constitutive prescriptions wit
h balance equations. We will show that\, when external sources are absent\
, an Eshelbian-like torque drives the passive reorientation of the fibres.
During the talk\, some issues underlying the definition of anisotropic an
d inelastic models will be discussed\, including the evolution of the symm
etry group of the material response due to the inelastic relaxation. Final
ly\, some prototype boundary value problems will be presented with the int
ent of highlighting the best experimental procedure to evaluate the consti
tutive coefficients of such a model.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giuseppe Tomassetti (Università Roma Tre)
DTSTART;VALUE=DATE-TIME:20201130T144000Z
DTEND;VALUE=DATE-TIME:20201130T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/8
DESCRIPTION:Title: Shape programming of a magnetic elastica\nby Giuseppe Tomassett
i (Università Roma Tre) as part of Nečas Seminar on Continuum Mechan
ics\n\n\nAbstract\nWe consider a cantilever beam which possesses a possibl
y non-uniform permanent magnetization\, and whose shape is controlled by a
n applied magnetic field. We model the beam as a plane elastic curve and w
e suppose that the magnetic field acts upon the beam by means of a distrib
uted couple that pulls the magnetization towards its direction. Given a li
st of target shapes\, we look for a design of the magnetization profile an
d for a list of controls such that the shapes assumed by the beam when act
ed upon by the controls are as close as possible to the targets\, in an av
eraged sense. To this effect\, we formulate and solve an optimal design an
d control problem leading to the minimization of a functional which we stu
dy by both direct and indirect methods. In particular\, we prove that mini
mizers exist\, solve the associated Lagrange-multiplier formulation (besid
es non-generic cases)\, and are unique at least for sufficiently low inten
sities of the controlling magnetic fields. To achieve the latter result\,
we use two nested fixed-point arguments relying on the Lagrange-multiplier
formulation of the problem\, a method which also suggests a numerical sch
eme. Various relevant open question are also discussed.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charlotte Perrin (CNRS Marseille)
DTSTART;VALUE=DATE-TIME:20201123T144000Z
DTEND;VALUE=DATE-TIME:20201123T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/9
DESCRIPTION:Title: Compressible Euler equations under a maximal density constraint\nb
y Charlotte Perrin (CNRS Marseille) as part of Nečas Seminar on Continuum
Mechanics\n\n\nAbstract\nIn this talk\, I will present recent results on
solutions to a one-dimensional Euler system coupling compressible and inco
mpressible phases. With this original fluid system we intend to model cong
estion (or saturation) phenomena in heterogeneous flows (mixtures\, wave-s
tructure interactions\, collective motion\, etc.). Here the compressible-i
ncompressible model will be seen as the limit of a fully compressible Eule
r system endowed with a singular pressure law. The goal of the talk is to
present theoretical results concerning this singular limit. This is a join
t work with Roberta Bianchini.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tai-Peng Tsai (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20201214T153000Z
DTEND;VALUE=DATE-TIME:20201214T170000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/10
DESCRIPTION:Title: The Green tensor of the nonstationary Stokes system in the half space
\nby Tai-Peng Tsai (University of British Columbia) as part of Nečas
Seminar on Continuum Mechanics\n\n\nAbstract\nWe prove the first-ever poin
twise estimates of the (unrestricted) Green tensor and\nthe associated pre
ssure tensor of the nonstationary Stokes system in the half-space\, for\ne
very space dimension greater than one. The force field is not necessarily
assumed to\nbe solenoidal. The key is to find a suitable Green tensor form
ula that maximizes the\ntangential decay\, showing in particular the integ
rability of Green tensor derivatives.\nWith its pointwise estimates\, we s
how the symmetry of the Green tensor\, which in\nturn improves pointwise e
stimates. We also study how the solutions converge to the\ninitial data\,
and the (infinitely many) restricted Green tensors acting on solenoidal\nv
ector fields. As applications\, we give new proofs of the existence of mil
d solutions of the\nNavier-Stokes equations in Lq\, pointwise decay\, and
uniformly local Lq spaces in the\nhalf-space.\nThis talk is based on arXiv
:2011.00134\, a joint work with Kyungkeun Kang\, Baishun\nLai and Chen-Chi
h Lai.\n\nThis seminar session will exceptionally start at 16:30.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnab Roy (Math. Inst. Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20201207T144000Z
DTEND;VALUE=DATE-TIME:20201207T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/11
DESCRIPTION:Title: Existence of strong solutions for a system of interaction between a c
ompressible viscous fluid and a wave equation\nby Arnab Roy (Math. Ins
t. Czech Academy of Sciences) as part of Nečas Seminar on Continuum Mecha
nics\n\n\nAbstract\nIn this talk\, we consider a fluid-structure interacti
on system\nwhere the fluid is viscous and compressible and where the stru
cture is\na part of the boundary of the fluid domain and is deformable. T
he fluid\nis governed by the barotropic compressible Navier-Stokes system
whereas\nthe structure displacement is described by a wave equation. The\n
reference configuration for the fluid domain is a rectangular cuboid\nwith
the elastic structure being the top face. We use a modified\nLagrangian c
hange of variables to transform the moving fluid domain into\nthe rectangu
lar cuboid and then analyze the corresponding linear system\ncoupling a tr
ansport equation (for the density)\, a heat-type equation\nand a wave equa
tion. The corresponding results for this linear system\nand estimations of
the coefficients coming from the change of variables\nallow us to perform
a fixed point argument and to prove the existence\nand uniqueness of stro
ng solutions for the nonlinear system\, locally in\ntime.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karoline Disser (Universitaet Kassel)
DTSTART;VALUE=DATE-TIME:20210104T144000Z
DTEND;VALUE=DATE-TIME:20210104T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/12
DESCRIPTION:Title: Global existence and stability for dissipative processes couple
d across volume and surface\nby Karoline Disser (Universitaet Kassel
) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nThe mode
lling of technological and biological processes and devices is\noften char
acterized by non-smoothness: material edges and corners\,\nabruptly changi
ng material properties and a large scope of relevant\ntemporal and spatial
scales. From a PDE point-of-view\, we need to deal\nwith domains of low b
oundary regularity\, mixed and dynamic boundary\nconditions\, degeneracy a
nd discontinuity of parameters\, and\, possibly\nafter rescaling\, with th
e coupling of dynamics across voulme and\nlower-dimensional interfaces or
surfaces.\n\nIn this talk\, I want to consider models of non-linear\nreact
ion-drift-diffusion type in non-smooth and/or volume-surface\nsettings and
discuss their analysis based on the choice of specific\nfunctional analyt
ic settings. The aim is to discuss some aspects of the\ninteraction of the
rmodynamically consistent modelling and the analysis\nof the PDE and to es
tablish strategies for simultaneously dealing with\nnon-linearity and non-
smoothness.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210111T144000Z
DTEND;VALUE=DATE-TIME:20210111T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/13
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210118T144000Z
DTEND;VALUE=DATE-TIME:20210118T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/14
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210125T144000Z
DTEND;VALUE=DATE-TIME:20210125T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/15
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210201T144000Z
DTEND;VALUE=DATE-TIME:20210201T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/16
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210208T144000Z
DTEND;VALUE=DATE-TIME:20210208T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/17
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210215T144000Z
DTEND;VALUE=DATE-TIME:20210215T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/18
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20210222T144000Z
DTEND;VALUE=DATE-TIME:20210222T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/19
DESCRIPTION:Title: No lecture\nby semester break as part of Nečas Seminar on Contin
uum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Easter Monday
DTSTART;VALUE=DATE-TIME:20210405T134000Z
DTEND;VALUE=DATE-TIME:20210405T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/20
DESCRIPTION:Title: No lecture\nby Easter Monday as part of Nečas Seminar on Continu
um Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jiří Outrata (ÚTIA\, Czech Acad. Sci.)
DTSTART;VALUE=DATE-TIME:20210301T144000Z
DTEND;VALUE=DATE-TIME:20210301T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/21
DESCRIPTION:Title: On the solution of static contact problems with Coulomb friction via
the semismooth* Newton method\nby Jiří Outrata (ÚTIA\, Czech Acad.
Sci.) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nThe
lecture deals with application of a new Newton-type method to the numeric
al solution of discrete 3D contact problems\nwith Coulomb friction. This m
ethod suits well to the solution of inclusions and the resulting conceptua
l algorithm exhibits\,\nunder appropriate conditions\, the local superline
ar convergence. After a description of the method a new (primal) model\nfo
r the considered contact problem\, amenable to the application of the new
method\, will be presented. The second part of\nthe talk is then devoted t
o an efficient implementation of the general algorithm and to numerical te
sts. Throughout the whole\nlecture\, various tools of modern variational a
nalysis will be employed.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Malte Kampschulte (Charles University)
DTSTART;VALUE=DATE-TIME:20210322T144000Z
DTEND;VALUE=DATE-TIME:20210322T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/22
DESCRIPTION:Title: Minimizing movements and a two-scale method for nonconvex problems in
volving inertia\nby Malte Kampschulte (Charles University) as part of
Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nWhen dealing with ful
ly nonlinear\, nonconvex\, quasistatic (i.e. inertialess) problems in cont
inuum mechanics\, de Giorgi's method of minimizing movements has long been
a staple for existence proofs. However by its very nature\, it has always
been restricted to purely dissipative\, gradient flow-type systems. The a
im of this talk is to present a new two-scale method\, developed jointly w
ith B. Benešová and S. Schwarzacher\, which allows to add inertial\, con
servative effects by using the minimizing movements method as a stepping s
tone to solve an approximative time-delayed problem in the same nonlinear\
, nonconvex state space. Using a flow-map approach\, this method is not on
ly able to cope with problems in Lagrangian\, but also with those in Euler
ian and even mixed formulations. While the method itself is quite general\
, we will illustrate its application at several examples involving solids\
, fluids and their interaction.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eitan Tadmor (University of Maryland\, College Park)
DTSTART;VALUE=DATE-TIME:20210329T134000Z
DTEND;VALUE=DATE-TIME:20210329T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/23
DESCRIPTION:Title: Emergent behavior in swarming hydrodynamics\nby Eitan Tadmor (Uni
versity of Maryland\, College Park) as part of Nečas Seminar on Continuum
Mechanics\n\n\nAbstract\nI will discuss recent developments in our study
of swarming \ndynamics.\nA main question of interest is the emergent behav
ior which we \ncharacterize by\nspectral analysis\, covering different cla
sses of long-range and \nshort-range communication kernels.\nThese includ
e examples of metric-based and topologically-based kernels\, \nand kernels
derived from a unified paradigm of anticipation.\nIn the canonical case o
f metric-based short-range kernels\, we derive \nlower-bounds on the spect
ral gap\,\nindependent of thermal equilibrium (no closure for the pressure
)\, which \nyield an emergent behavior of non-vacuous smooth solutions.\nT
he latter are known to exist in one- and two space dimensions and we \nse
ttle the question of existence for arbitrary dimension.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antonio J. Gil (University of Swansea\, UK)
DTSTART;VALUE=DATE-TIME:20210308T144000Z
DTEND;VALUE=DATE-TIME:20210308T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/24
DESCRIPTION:Title: On the use of mixed formulations for computational polyconvexity an
d multi-variable convexity\nby Antonio J. Gil (University of Swansea\,
UK) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nThe c
omputational modelling of large strain multi-physics problems is nowadays
an area of intensive research by numerous scientists. Among problems of th
is kind\, two pressing applications underpin the motivation behind this pr
esentation. On the one hand\, the in-silico design of highly flexible diel
ectric elastomers for soft robotics applications and\, on the other hand\,
the realistic simulation of the electromechanical interactions of the car
diac muscle from the physiological and pathological standpoints. In both a
pplications\, the requirement for extremely accurate and stable results at
\, possibly\, large values of the field variables (i.e. strains and electr
ic/cardiac potential) proves very challenging from the computational point
of view.\nThe presentation starts by revisiting the now well-accepted req
uirement of polyconvexity (a sufficient condition for rank-one convexity)
in the case of reversible hyperelasticity\, where the strain energy functi
onal is described by a convex combination of the minors of the deformation
gradient tensor. We then extend this concept to the case of energies whic
h depend on non-strain based variables\, for instance\, other physical mea
sures such as the electric displacement\, leading to the introduction of a
new computational paradigm\, Multi-Variable Convexity. Crucially\, this n
ew definition of the internal energy enables ellipticity to be extended to
the entire range of deformations and electric fields and\, thus\, spuriou
s numerical instabilities can then effectively be removed from the model w
hilst maintaining real physical instabilities.\nThe polyconvexity of the e
nergy functional with respect to its set of arguments guarantees the defin
ition of well-posed counterpart work conjugates\, where a one to one (inve
rtible) relationship can be established. This ensures the existence of alt
ernative energy potentials via the use of partial or total Legendre transf
orms and opens up the possibility for new extended Hu–Washizu-type varia
tional principles in terms of using various interpolation spaces for the d
ifferent unknown fields\, leading to enhanced type of formulations. A seri
es of examples will be presented demonstrating the potential of this new p
aradigm when coupled with the use of Finite Element type discretisation te
chniques.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adrian Muntean (Karlstadt University)
DTSTART;VALUE=DATE-TIME:20210426T134000Z
DTEND;VALUE=DATE-TIME:20210426T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/25
DESCRIPTION:Title: Does vesicle micro-dynamics enhance the signaling among plants macro-
transport? Multiscale discussions around a model problem\nby Adrian Mu
ntean (Karlstadt University) as part of Nečas Seminar on Continuum Mechan
ics\n\n\nAbstract\nWe study a transport problem for signaling among plants
in the context of measure-valued equations. We report on preliminary resu
lts concerning the modeling and mathematical analysis of a reaction-diffus
ion scenario involving the macroscopic diffusion of signaling molecules e
nhanced by the presence of a finite number of microscopic vesicles - pocke
ts with own dynamics able to capture and release signals as a relay system
. The coupling between the macroscopic and microscopic spatial scales reli
es on the use of a two-scale transmission condition and benefits of the po
sing of the problem in terms of measures. Mild solutions to our problem wi
ll turn to exist and will also be positive weak solutions. A couple of ope
n questions at the modeling\, mathematical analysis\, and simulation level
s will be pointed out. This is a joint work with Sander Hille (Leiden\, NL
) and is supported financially by the KVA’s G. S. Magnussonsfond.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valerio Pagliari (TU Vienna)
DTSTART;VALUE=DATE-TIME:20210412T134000Z
DTEND;VALUE=DATE-TIME:20210412T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/26
DESCRIPTION:Title: Convergence of nonlocal geometric flows to anisotropic mean curvature
motion\nby Valerio Pagliari (TU Vienna) as part of Nečas Seminar on
Continuum Mechanics\n\n\nAbstract\nWe consider the Cauchy problem for moti
ons by nonlocal curvature\, whose \nwell-posedness may be established in t
he framework of viscosity solutions.\nWe show that a suitable rescaling of
the nonlocal curvature induces a \nlocalisation effect\, that is\, as the
scaling parameter tends to 0\,\nwe retrieve an anisotropic mean curvature
functional. From this fact\, \nthanks to the theory of geometric barriers
by De Giorgi\,\nwe prove that the solutions to the rescaled nonlocal moti
ons locally \nuniformly converge to the solution of the local flow.\nThe t
alk is based on joint work with A. Cesaroni (Padova).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Denis Bonheure (Université Libre de Bruxelles)
DTSTART;VALUE=DATE-TIME:20210510T134000Z
DTEND;VALUE=DATE-TIME:20210510T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/27
DESCRIPTION:Title: Equilibrium configuration of a rectangular obstacle immersed in a cha
nnel flow\nby Denis Bonheure (Université Libre de Bruxelles) as pa
rt of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nFluid flows aro
und an obstacle generate vortices which\, in turn\, generate lift forces o
n the obstacle. Therefore\, even in a perfectly symmetric framework equili
brium positions may be asymmetric. We show that this is not the case for a
Poiseuille flow in an unbounded 2D channel\, at least for small Reynolds
number and flow rate. We consider both the cases of vertically moving obst
acles and obstacles rotating around a fixed pin.\nJoint work with P.G. Gal
di and F. Gazzola\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maria Neuss-Radu (University of Erlangen-Nuremberg)
DTSTART;VALUE=DATE-TIME:20210524T134000Z
DTEND;VALUE=DATE-TIME:20210524T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/28
DESCRIPTION:Title: Homogenization of a reaction-diffusion-advection problem in an evolvi
ng micro-domain and including nonlinear boundary conditions\nby Maria
Neuss-Radu (University of Erlangen-Nuremberg) as part of Nečas Seminar o
n Continuum Mechanics\n\n\nAbstract\nWe consider a reaction-diffusion-adve
ction problem in a \nperforated medium\, with nonlinear reactions in the b
ulk and at the \nmicroscopic boundary\, and slow diffusion scaling. The mi
crostructure \nchanges in time\; the microstructural evolution is known a
priori. The \naim of the paper is the rigorous derivation of a homogenized
model. We \nuse appropriately scaled function spaces\, which allow us to
show \ncompactness results\, especially regarding the time-derivative and
we \nprove strong two-scale compactness results of Kolmogorov-Simon-type\,
\nwhich allow to pass to the limit in the nonlinear terms. The derived \n
macroscopic model depends on the micro- and the macro-variable\, and the \
nevolution of the underlying microstructure is approximated by time- and \
nspace-dependent reference elements. This is a joint work with Markus \nGa
hn (University of Heidelberg) and Iuliu Sorin Pop (Hasselt \nUniversity).\
n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Patrick Dondl (University of Freiburg)
DTSTART;VALUE=DATE-TIME:20210315T144000Z
DTEND;VALUE=DATE-TIME:20210315T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/29
DESCRIPTION:Title: Energetic bounds for paperboard delamination under bending\nby Pa
trick Dondl (University of Freiburg) as part of Nečas Seminar on Continuu
m Mechanics\n\n\nAbstract\nPaperboard is an engineering material consistin
g of a number of separate sheets of paper\, that have been bonded together
. Experimental evidence shows that paperboard undergoing bending develops
phenomenologically plastic hinges. We consider a nonlinearly elastic mathe
matical model for paperboard\, allowing debonding of the sheets at a given
cost per unit area. Analysis of our model predicts a number of different
regimes\, including somewhere bending is concentrated in delaminated hinge
s\, where the mid-plane of each individual layer may deform isometrically.
This is joint work with Sergio Conti (Bonn) and Julia Orlik (Kaiserslaute
rn).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Summer break
DTSTART;VALUE=DATE-TIME:20210607T134000Z
DTEND;VALUE=DATE-TIME:20210607T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/30
DESCRIPTION:Title: We'll meet again in October 2021\nby Summer break as part of Neč
as Seminar on Continuum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Březina (TU Liberec)
DTSTART;VALUE=DATE-TIME:20210503T134000Z
DTEND;VALUE=DATE-TIME:20210503T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/31
DESCRIPTION:Title: Continuum-fracture approach to modelling crystalline rock\nby Jan
Březina (TU Liberec) as part of Nečas Seminar on Continuum Mechanics\n\
n\nAbstract\nWe start with a statistical description of the fracture netwo
rks in real (crystalline) rocks and related heterogeneous material propert
ies. Next\, we shall present continuum-fracture (CF) approach to the descr
iption of the processes in real rock. CF description has been consistently
applied in the Flow123d simulator of THMC proceses. We will summarize sim
ulated processes\, numerical schemes\, and software tools. Finally\, we pr
esent particular applications in the safety of deep nuclear waste reposito
ries and the efficiency of enhanced geothermal systems.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Stebel (TU Liberec)
DTSTART;VALUE=DATE-TIME:20210517T134000Z
DTEND;VALUE=DATE-TIME:20210517T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/32
DESCRIPTION:Title: Continuum-fracture models of porous media processes: derivation and a
nalysis\nby Jan Stebel (TU Liberec) as part of Nečas Seminar on Conti
nuum Mechanics\n\n\nAbstract\nMathematical modelling of heterogeneous mate
rials such as granitic rocks requires special treatment of fractures. We p
resent the derivation of the so-called continuum-fracture model for two ty
pes of problems: advection-diffusion process (e.g. transport of contaminan
ts or heat) and hydro-mechanical coupling based on Biot’s theory. For th
e hydro-mechanical problem we distinguish the linear case and the case of
contact and shear-dilation conditions at fractures. Existence of weak sol
utions is established. The problem is discretized by the finite element me
thod and solved using the so-called fixed-stress iterative splitting whose
convergence is analyzed.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Milan Pokorný (Mathematical Institute\, Charles Universiy)
DTSTART;VALUE=DATE-TIME:20210531T134000Z
DTEND;VALUE=DATE-TIME:20210531T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/33
DESCRIPTION:Title: Homogenization of Navier--Stokes--Fourier system in domains with tiny
holes\nby Milan Pokorný (Mathematical Institute\, Charles Universiy)
as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nWe consid
er the compressible Navier--Stokes--Fourier system in a domain with large
number of holes. Under the assumption that the holes are sufficiently smal
l\, together with certain standard assumptions on the adiabatic exponent a
nd the behaviour of the heat conductivity\, we show that if passing simult
aneously with the number of holes to infinity and their size to zero\, in
the limit we obtain again solution to the compressible Navier--Stokes--Fou
rier system in the domain without holes. The result holds both for the ste
ady and evolutionary problem. It is a joint work with Yong Lu (Nanjing Uni
versity) and Emil Skříšovský (Charles University\, Prague).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manuel Friedrich (University of Muenster)
DTSTART;VALUE=DATE-TIME:20210419T134000Z
DTEND;VALUE=DATE-TIME:20210419T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/34
DESCRIPTION:Title: Emergence of rigid polycrystals from atomistic systems\nby Manuel
Friedrich (University of Muenster) as part of Nečas Seminar on Continuum
Mechanics\n\n\nAbstract\nWe investigate the emergence of rigid polycrysta
lline structures from atomistic particle systems. The atomic interaction i
s governed by a suitably normalized pair interaction energy\, where the `s
ticky disk’ interaction potential models the atoms as hard spheres that
interact when they are tangential. The discrete energy is frame invariant
and no underlying reference lattice on the atomistic configurations is ass
umed. By means of Gamma-convergence\, we characterize the asymptotic behav
ior of configurations with finite surface energy scaling in the infinite p
article limit. The effective continuum theory is described in terms of a p
iecewise constant field delineating the local orientation and micro-transl
ation of the configuration. The limiting energy is local and concentrated
on the grain boundaries\, i.e.\, on the boundaries of the zones where the
underlying microscopic configuration has constant parameters. The correspo
nding surface energy density depends on the relative orientation of the tw
o grains\, their microscopic translation misfit\, and the normal to the in
terface. Joint work with Leonard Kreutz (Münster) and Bernd Schmidt (Augs
burg).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Zeman (Faculty of Civil Engineering\, Czech Tech. Uni.)
DTSTART;VALUE=DATE-TIME:20211004T134000Z
DTEND;VALUE=DATE-TIME:20211004T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/35
DESCRIPTION:Title: Designing optimal reinforcement for high-performance composite tubes
with semidefinite programming\nby Jan Zeman (Faculty of Civil Engineer
ing\, Czech Tech. Uni.) as part of Nečas Seminar on Continuum Mechanics\n
\nLecture held in K3 Karlin.\n\nAbstract\nFueled by their excellent stiffn
ess-to-weight ratio and the availability of mature manufacturing technolog
ies\, filament wound carbon fiber reinforced polymers represent ideal mate
rials for thin-walled laminate structures. However\, their strong anisotro
py reduces structural resistance to wall instabilities under shear and buc
kling. Increasing laminate thickness degrades weight and structural effici
encies and the application of a dense internal core is often uneconomical
and labor-intensive. In this contribution\, we introduce a convex linear s
emidefinite programming formulation for truss topology optimization to des
ign an efficient non-uniform lattice-like internal structure. The internal
structure not only reduces the effect of wall instabilities\, mirrored in
the increase of the fundamental free-vibration eigenfrequency\, but also
keeps weight low\, secures manufacturability using conventional three-dime
nsional printers\, and withstands the loads induced during the production
process. We showcase a fully automatic procedure in detail for the design\
, prototype manufacturing\, and verification of a simply-supported composi
te machine tool component\, including validation with roving hammer tests.
The results confirm that the 3D-printed optimized internal structure almo
st doubles the fundamental free-vibration eigenfrequency\, allowing to inc
rease the working frequency of the machine tool\, even though the ratio be
tween elastic properties of the carbon composite and the ABS polymer used
for 3D printing exceeds two orders of magnitude.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hanuš Seiner (Inst. of Thermomechanics\, CAS)
DTSTART;VALUE=DATE-TIME:20211018T134000Z
DTEND;VALUE=DATE-TIME:20211018T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/36
DESCRIPTION:Title: Landau-energy landscape reconstruction for a Ni-Fe-Ga(Co) Shape Memor
y Alloy\nby Hanuš Seiner (Inst. of Thermomechanics\, CAS) as part of
Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nIn the framework of c
ontinuum mechanics\, the thermo-mechanical behavior of shape memory alloys
is often described using the Landau-theory approach\, where the multi-wel
l free energy density of the crystal is approximated by a polynomial with
the required number of minima and energy barriers. Here we show how the en
ergy landscape (in the strain-temperature space) can be reconstructed from
experiments\, and how accurately this energy is approximated by the Landa
u-theory ansatz. Elastic behavior of single crystals of Ni-Fe-Ga(Co) ferro
magnetic shape memory alloys is studied in a broad temperature range. Usin
g tensile stress-strain measurements and ultrasonic characterization\, we
prove that austenite and martensite phases of the given alloy exhibit stro
ngly non-linear elastic responses\, and we utilize the non-linear stress-s
train data for constructing an energy function describing the observed beh
avior in the context of the Landau theory. We discuss the implications of
the constructed model\, focusing in particular to the so-called critical p
oint in the energy landscape\, where the austenite-martensite transition b
ecomes weakly second-order.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Katharina Brazda (University of Vienna)
DTSTART;VALUE=DATE-TIME:20211025T134000Z
DTEND;VALUE=DATE-TIME:20211025T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/37
DESCRIPTION:Title: Multiphase biological membranes\nby Katharina Brazda (University
of Vienna) as part of Nečas Seminar on Continuum Mechanics\n\nLecture hel
d in K3 Karlin\, Sokolovska 83\, Praha 8.\n\nAbstract\nBiological membrane
s are thin layers of lipid molecules. Mechanically\,\nthey can be describe
d as incompressible viscous fluid surfaces with\nbending elasticity. The e
quilibrium shapes of homogeneous membranes\nminimize the Canham-Helfrich e
nergy under area and enclosed volume\nconstraints. In particular\, this va
riational model explains the typical\nbiconcave shape of human red blood c
ells. Configurations of\nheterogeneous biomembranes also feature an intrig
uing coupling effect\nbetween composition and geometry\, which originates
from their inherent\nfluidity. In this talk\, we introduce these models an
d present an\nexistence result for multiphase membranes with sharp phase i
nterfaces\,\nobtained in the framework of oriented curvature varifolds.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Filippo Riva (University of Pavia)
DTSTART;VALUE=DATE-TIME:20211011T134000Z
DTEND;VALUE=DATE-TIME:20211011T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/38
DESCRIPTION:Title: Inertial Balanced Viscosity solutions to rate-independent systems
\nby Filippo Riva (University of Pavia) as part of Nečas Seminar on Conti
nuum Mechanics\n\n\nAbstract\nRate-independent evolutions frequently occur
in mechanics when \nthe problem\nunder consideration presents such small
rate-dependent effects\, as \ninertia or viscosity\, that can be neglected
. If the driving potential \nenergy is nonconvex any (reasonable) solution
necessarily exhibits \ntime-discontinuities. To describe the behaviour of
the jumps\, in the \nlast decades the notions of Energetic and Balanced V
iscosity solutions \nhave been developed\, the latter as a refinement of t
he former. While for \nEnergetic solutions the cost at jumps is described
only in terms of the \nrate-independent dissipation potential\, in the cas
e of Balanced \nViscosity solutions it arises from a suitable coupling bet
ween this \ndissipation potential and a smaller and smaller viscosity pote
ntial\, \nwhich is reminiscent of an original presence of viscous damping.
\nIn this talk we present a novel notion of solution to rate-independent \
nsystems\, named Inertial Balanced Viscosity (IBV) solution\, which in \na
ddition takes into account small inertial effects. Differently from the \n
previous cases\, now the jump cost turns out to be rate-dependent. In \nfi
nite dimension\, we show how IBV solutions can be obtained as a \nvanishin
g inertia and viscosity limit of dynamic evolutions\, and we \nintroduce a
multiscale Minimizing Movements algorithm which can be used \nto build su
ch solutions.\nThis is a joint work with G. Scilla and F. Solombrino.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Bevan (University of Surrey\, GB)
DTSTART;VALUE=DATE-TIME:20211108T144000Z
DTEND;VALUE=DATE-TIME:20211108T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/39
DESCRIPTION:Title: Interior 'buckling' and non-uniqueness in a class of incompressible v
ariational problems\nby Jonathan Bevan (University of Surrey\, GB) as
part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nThe talk is a
bout a class variational problems whose associated energies $E_{\\eps}$ ca
n be thought of as perturbations of the Dirichlet energy. These energies
have countably many pairs of planar\, measure-preserving stationary points
$u^n_{\\pm}$ with the properties that (a) $E_{\\eps}(u^n_+)=E_{\\eps}(u^n
_-)$ and (b) the maps $u^n_{\\pm}$ cause `buckling' at the centre $0$ of t
he unit ball $B$ in $\\mathbb{R}^2$ while acting as the identity on $\\par
tial B$. Numerical calculations show that $n$ can be treated as a proxy
for the `number of buckles' that occur at $0$\, and that\, as one might ex
pect\, $E_{\\eps}(u^n_{\\pm})$ increases as $n$ does. This is joint work
with J. Deane.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Campbell (Universita Hradec Králové)
DTSTART;VALUE=DATE-TIME:20211129T144000Z
DTEND;VALUE=DATE-TIME:20211129T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/40
DESCRIPTION:Title: Closures of planar BV homeomorphisms and the relaxation of functional
s with linear growth\nby Daniel Campbell (Universita Hradec Králové)
as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nMotivated
by relaxation results of Kristensen and Rindler\, and of Benešová\, Kr
ömer and Kružík for BV maps\, we study the class of strict limits of BV
planar homeomorphisms. We show that\, although such maps need not be inje
ctive and are not necessarily continuous on almost every line\, the class
has a reasonable behavior expected for limit of elastic deformations. By a
characterization of the classes of strict and area-strict limits of BV ho
meomorphisms we show that these classes coincide. \n\nThis is based on joi
nt works with S. Hencl\, A. Kauranen and E. Radici.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ulisse Stefanelli (University of Vienna)
DTSTART;VALUE=DATE-TIME:20211122T144000Z
DTEND;VALUE=DATE-TIME:20211122T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/41
DESCRIPTION:Title: Existence results for a morphoelastic model\nby Ulisse Stefanelli
(University of Vienna) as part of Nečas Seminar on Continuum Mechanics\n
\n\nAbstract\nI will report on a recent work in collaboration with Elisa D
avoli (TU Wien) and Katerina Nik (University of Vienna) on a three-dimensi
onal quasistatic morpholelastic model. The mechanical response of the body
and its growth are modeled by an interplay of hyperelastic energy minimiz
ation and growth dynamics. A first existence result is obtained by regular
ization and time-discretization\, also taking advantage of an exponential-
update scheme. We then allow the growth dynamics to depend on an additiona
l scalar field\, say a nutrient\, and formulate an optimal control problem
. Eventually\, we tackle the existence of coupled morphoelastic and nutrie
nt solutions\, when the latter is allowed to diffuse and interact with the
growing body.\n\nThe preprint is available as arXiv:2110.05566.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tomáš Roubíček (Math. Inst. of Charles University)
DTSTART;VALUE=DATE-TIME:20211101T144000Z
DTEND;VALUE=DATE-TIME:20211101T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/42
DESCRIPTION:Title: Visco-plastic elastodynamics and poro-elastodynamics at large deforma
tions by Eulerian approaches\nby Tomáš Roubíček (Math. Inst. of Ch
arles University) as part of Nečas Seminar on Continuum Mechanics\n\n\nAb
stract\nTwo models of hardening-free plasticity at large deformations\nwil
l be presented in Eulerian rate formulation based on two\nstandard concept
s\, Green-Naghdi additive decomposition\nand Kroner-Lee-Liu multiplicative
decomposition of the\ntotal strain. Extension towards poroelasticity and\
nthermodynamics will be outlined\, too.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Philipp Reiter (TU Chemnitz)
DTSTART;VALUE=DATE-TIME:20211115T144000Z
DTEND;VALUE=DATE-TIME:20211115T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/43
DESCRIPTION:Title: Symmetric elastic knots\nby Philipp Reiter (TU Chemnitz) as part
of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nMinimizing the ben
ding energy within knot classes leads to the concept \nof elastic knots. M
otivated by numerical experiments we prescribe \ndihedral symmetry and est
ablish existence of dihedrally symmetric \nelastic knots for knot classes
admitting this type of symmetry. Among \nother results we prove that the d
ihedral elastic trefoil is the union of \ntwo circles that form a (planar)
figure-eight. We also discuss some \ngeneralizations and limitations rega
rding other symmetries and knot classes.\n\nThis is joint work with Alexan
dra Gilsbach and Heiko von der Mosel.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stanislav Sysala (Institute of Geonics\, Cz. Acad. Sci.)
DTSTART;VALUE=DATE-TIME:20211206T144000Z
DTEND;VALUE=DATE-TIME:20211206T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/44
DESCRIPTION:Title: Saddle-point problems with bilinear Lagrangian and convex constraint
s: analysis\, numerical solution and applications\nby Stanislav Sysala
(Institute of Geonics\, Cz. Acad. Sci.) as part of Nečas Seminar on Cont
inuum Mechanics\n\n\nAbstract\nThe first part of the talk is concerned wit
h an abstract inf-sup problem \ngenerated by a bilinear Lagrangian and con
vex constraints. The \nconditions that guarantee no gap between the inf-su
p and related sup-inf \nproblems are studied. A particular attention is de
voted to the inf-sup \ncondition defined for convex cones in function spac
es. Next\, a \nregularization method convenient for solving the inf-sup pr
oblem is \nanalyzed and a computable majorant of the critical (inf-sup) va
lue is \nderived for purposes of a posteriori error analysis of numerical
\nresults. The second part of the talk is devoted to applications of the \
nabstract framework to continuum mechanics. In particular\, examples of \n
limit load problems and similar ones arising in classical plasticity\, \ng
radient plasticity and delamination are introduced. The presented \nresult
s follow from the joint work with Daya B. Reddy\, Sergey Repin and \nJaros
lav Haslinger.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amrita Gosh (University of Bonn)
DTSTART;VALUE=DATE-TIME:20211213T144000Z
DTEND;VALUE=DATE-TIME:20211213T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/45
DESCRIPTION:Title: On Shikhmurzaev’s approach to the Contact Line Problem\nby Amri
ta Gosh (University of Bonn) as part of Nečas Seminar on Continuum Mechan
ics\n\n\nAbstract\nI will discuss the general moving contact line problem\
, arising from many fluid mechanics\nphenomena. The classical formulation
of this model with the no-slip (Dirichlet) boundary\ncondition for velocit
ies at the liquid-solid interface gives rise to a non-integrable singulari
ty\nof the shear stress\, which is known as the ”moving contact line par
adox”. Y. Shikhmurzaev\nproposed (1993) a different approach to solve th
is issue. This approach\, apart from the\nclassical conservation equations
\, formulates the boundary conditions for the equations in\nthe bulk phase
s in an elaborate way\, which can be viewed as a generalization of the exi
sting\nmodels in the literature\, although generated from a different unde
rlying theory. After giving\nan overview of this model\, I would like to d
erive a thin film approximation of Shikhmurzaev’s\nmodel to compare with
the other solution model of the contact line problem.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christmas break (Christmas break)
DTSTART;VALUE=DATE-TIME:20211227T144000Z
DTEND;VALUE=DATE-TIME:20211227T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/46
DESCRIPTION:Title: Christmas break\nby Christmas break (Christmas break) as part of
Nečas Seminar on Continuum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christmas break (Christmas break)
DTSTART;VALUE=DATE-TIME:20211220T144000Z
DTEND;VALUE=DATE-TIME:20211220T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/47
DESCRIPTION:Title: Christmas break\nby Christmas break (Christmas break) as part of
Nečas Seminar on Continuum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karel Tůma (Mathematical Institute\, Charles University)
DTSTART;VALUE=DATE-TIME:20220103T144000Z
DTEND;VALUE=DATE-TIME:20220103T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/48
DESCRIPTION:Title: Finite strain phase-field model for martensitic transformation: Large
-scale finite element simulations\nby Karel Tůma (Mathematical Instit
ute\, Charles University) as part of Nečas Seminar on Continuum Mechanics
\n\n\nAbstract\nMartensitic transformation is a first-order solid-solid di
ffusionless transformation that occurs between the parent phase (austenite
) and the product phase (martensite) and is characterized by the microstru
cture evolution\, which is accompanied by the formation\, propagation\, an
d annihilation of the interfaces. In shape memory alloys\, the microstruct
ure evolution is the mechanism behind the properties such as pseudoelastic
ity and shape memory effect. In general\, due to the incompatibility betwe
en austenite and a single variant of martensite\, the martensitic transfor
mation is realized via the formation of complex twinning microstructure. \
nA recently developed phase-field model for multivariant martensitic trans
formation is implemented using the finite element method and used to compu
te large-scale simulations reaching 150 million degrees of freedom. The c
omputational problems are quite expensive due to the fact that high mesh d
ensity is needed to capture the detailed microstructure\, see attached fig
ure. Our implementation has shown robustness and good parallel scaling per
formance. Having this model\, the goal is to perform a systematic investig
ation of the effect of crystal lattice orientation and material anisotropy
on the indentation-induced microstructure evolution in CuAlNi shape memor
y alloy. To our knowledge\, such a comprehensive high-resolution microstru
cture-based modeling study has not been reported before. This is a joint w
ork with M. Rezaee-Hajidehi\, S. Stupkiewicz\, J. Hron and P. Farrell.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20220110T144000Z
DTEND;VALUE=DATE-TIME:20220110T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/49
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20220117T144000Z
DTEND;VALUE=DATE-TIME:20220117T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/50
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20220124T144000Z
DTEND;VALUE=DATE-TIME:20220124T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/51
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20220131T144000Z
DTEND;VALUE=DATE-TIME:20220131T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/52
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20220207T144000Z
DTEND;VALUE=DATE-TIME:20220207T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/53
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sabrine Chebbi (University of Tunisia\, El MANAR\, UTM)
DTSTART;VALUE=DATE-TIME:20220221T144000Z
DTEND;VALUE=DATE-TIME:20220221T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/54
DESCRIPTION:Title: The Energy decay rate of 1D and 2D Timoshenko systems. Theoretical a
nalysis and numerical simulation\nby Sabrine Chebbi (University of Tun
isia\, El MANAR\, UTM) as part of Nečas Seminar on Continuum Mechanics\n
\n\nAbstract\nWe focus on the behavior of the solutions of the Timoshenko
systems\nin dimensions 1 and 2 using the lower bound estimates of the ener
gy. We\nstudy a nonlinear damped one-dimensional thermo-elastic Timoshenko
system\nwhere the heat flux is given by the Cattaneo’s law. After deriv
ing the strong\nlower energy estimates\, we show the optimality for some e
xplicit examples.\nFurthermore\, we discuss the well-posedness and the dec
ay rate of the energy\nof the Mindlin-Timoshenko plate equations subject t
o a nonlinear dissipation\nacting on the rotation angles’equations. Late
r\, we perform a numerical sim-\nulation of the one-dimensional Timoshenko
system\, our approach is based\non adequate use of the finite element and
the finite difference methods\ngiving rise to a new scheme which characte
rizes the asymptotic behavior of\nthe discrete energy.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giusy Mazzone (Queen's University)
DTSTART;VALUE=DATE-TIME:20220502T134000Z
DTEND;VALUE=DATE-TIME:20220502T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/55
DESCRIPTION:Title: On partially dissipative systems\nby Giusy Mazzone (Queen's Unive
rsity) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nIn
this talk\, we will investigate the dynamics of three mechanical systems:
a rigid body with a damper\, a system of rigid bodies with a fluid-filled
gap\, and a harmonic oscillator in a fluid-filled pipe. The equations gove
rning the motion of these systems are “partially dissipative”\, in tha
t there exists an energy functional that decreases along the trajectories\
, while other physical variables are conserved or even excited during the
motion. The objective of our investigations is to describe the “stabiliz
ation properties” of the systems. By “stabilization” we mean either
convergence of each trajectory to a stationary solution or the existence o
f periodic solutions to the governing equations corresponding to forces wi
th arbitrary frequencies.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Pelech (WIAS Berlin)
DTSTART;VALUE=DATE-TIME:20220307T144000Z
DTEND;VALUE=DATE-TIME:20220307T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/56
DESCRIPTION:Title: Penrose-Fife model with activated phase transformation - Existence an
d effective model for slow-loading regimes.\nby Petr Pelech (WIAS Berl
in) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nWe stu
dy a non-autonomous system of two evolutionary PDEs\, an enhanced version
of the Penrose-Fife model introduced in 1990\, which first in history coup
led the Allen-Cahn phase-field equation with thermal effects in a thermody
namically consistent way. In our work we consider an activated phase trans
formation which makes the phase-field equation non-linear in time derivati
ve\; it contains an additional term that describes also the Coulomb dry fr
iction and whose analogues appear in rate-independent models of plasticity
or damage. Apart from proving the existence of solutions of the system\,
we investigate its effective behavior for the so-called slow-loading regim
es. There the internal time-scale introduced by phase-field viscosity and
thermal conductivity is much smaller than the time-scale of the loading\,
an external force acting on the system. Hence the system stays almost in i
ts equilibrium described by the static solution. However\, the limit of so
lutions (as the ratio of the time scales tends to zero) may not be charact
erized by the corresponding rate-independent model where the viscous-like
terms have been dropped. The reason is that the phase transformation is dr
iven by a non-convex thermodynamic potential and hence the solutions may d
evelop jumps in the limit. In order to resolve the jump's detailed traject
ory\, along which the viscous effects play a crucial role\, we use the so-
called Balanced-Viscosity (BV) solutions introduced by Efendiev and Mielke
in 2006. This work is a collaboration with Matthias Liero and Alexander M
ielke from WIAS Berlin.\n\nPenrose O.\, Fife P. C. - Thermodynamically Con
sistent Models of Phase-Field Type for the Kinetics of Phase Transitions (
1990)\n\nSprekels J.\, Zheng S. M. - Global smooth solutions to a thermody
namically consistent model of phase-field type in higher space dimensions
(1993)\n\nEfendiev M.\, Mielke A. - On the rate-independent limit of syst
ems with dry friction and small viscosity (2006)\n\nMielke A.\, Roubicek T
. - Rate-independent Systems Theory and Application (2015)\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Easter Monday
DTSTART;VALUE=DATE-TIME:20220418T134000Z
DTEND;VALUE=DATE-TIME:20220418T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/57
DESCRIPTION:Title: No lecture\nby Easter Monday as part of Nečas Seminar on Continu
um Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:George Avalos (UNIVERSITY of NEBRASKA–LINCOLN)
DTSTART;VALUE=DATE-TIME:20220516T134000Z
DTEND;VALUE=DATE-TIME:20220516T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/58
DESCRIPTION:Title: Concerning the strong and uniform decay of solutions to coupled flui
d/multilayered structure PDE dynamics\nby George Avalos (UNIVERSITY o
f NEBRASKA–LINCOLN) as part of Nečas Seminar on Continuum Mechanics\n\n
\nAbstract\nIn this talk\, we will discuss our recent work on a certain\n
multilayered structure-fluid interaction (FSI) which arises in the\n model
ing of vascular blood flow. The coupled PDE system under our\n considerati
on mathematically accounts for the fact that mammalian\n veins and arterie
s are typically composed of various layers of\n tissues: each layer will g
enerally manifest its own intrinsic material\n properties\, and will moreo
ver be separated from the other layers by\n thin elastic laminae. Conseque
ntly\, the resulting modeling FSI system\n will manifest an additional PDE
\, which evolves on the boundary\n interface\, so as to account for the th
in elastic layer. (This is in\n contrast to the FSI PDE’s which appear i
n the literature\, wherein\n elastic dynamics are largely absent on the bo
undary interface.) As\n such\, the PDE system will constitute a coupling o
f 3D fluid-2D\n elastic-3D elastic dynamics. For this multilayered FSI sys
tem\, we will\n in particular present results of strong stability for fini
te energy\n solutions\, and polynomial decay for sufficiently regular solu
tions.\n This is joint work with Pelin Güven Geredeli and Boris Muha.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:summer break
DTSTART;VALUE=DATE-TIME:20220523T134000Z
DTEND;VALUE=DATE-TIME:20220523T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/59
DESCRIPTION:Title: We will continue on Monday\, October 3\, 2022\nby summer break as
part of Nečas Seminar on Continuum Mechanics\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Václav Mácha (Inst. of Mathematics\, Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220228T144000Z
DTEND;VALUE=DATE-TIME:20220228T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/60
DESCRIPTION:Title: Fluids in moving domains\nby Václav Mácha (Inst. of Mathematics
\, Czech Academy of Sciences) as part of Nečas Seminar on Continuum Mecha
nics\n\n\nAbstract\nWe present several results concerning the flow of a\n
compressible heat-conducting fluid in a moving domain. We discuss the\n ex
istence of a weak solution. Next\, we tackle the low-Mach number\n limit a
nd we deduce the target system for the low-stratification case.\n The talk
is based on results obtained in collaboration with O. Kreml\,\n S. Nečas
ová and A. Wroblewska-Kaminska\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Justyna Ogorzaly (Jagiellonian University)
DTSTART;VALUE=DATE-TIME:20220404T134000Z
DTEND;VALUE=DATE-TIME:20220404T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/61
DESCRIPTION:Title: Variational-Hemivariational Inequalities with Applications to Contact
Mechanics\nby Justyna Ogorzaly (Jagiellonian University) as part of N
ečas Seminar on Continuum Mechanics\n\n\nAbstract\nWe will present the ex
istence and uniqueness results for the\nspecial classes of nonlinear varia
tional-hemivariational inequalities.\nThen\, we will consider concrete con
tact problems and we will show how\nthese problems lead to the different t
ype of variational-hemivariational\ninequalities.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henrik Schumacher (TU Chemnitz)
DTSTART;VALUE=DATE-TIME:20220509T134000Z
DTEND;VALUE=DATE-TIME:20220509T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/62
DESCRIPTION:Title: Repulsive Curves and Surfaces\nby Henrik Schumacher (TU Chemnitz)
as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nFunctiona
ls that penalize bending or stretching of a surface play a key role in geo
metric and scientific\ncomputing\, but to date have ignored a very basic r
equirement: in many situations\, surfaces must not pass\nthrough themselve
s or each other. This paper develops a numerical framework for optimizatio
n of surface\ngeometry while avoiding (self-)collision. The starting point
is the tangent-point energy\, which effectively pushes\napart pairs of po
ints that are close in space but distant along the surface. We develop a d
iscretization of\nthis energy for triangle meshes and introduce a novel ac
celeration scheme based on a fractional Sobolev inner\nproduct. In contras
t to similar schemes developed for curves (cf. [2])\, we avoid the complex
ity of building a\nmultiresolution mesh hierarchy by decomposing our preco
nditioner into two ordinary Poisson equations\, plus\nforward application
of a fractional differential operator. We further accelerate this scheme v
ia hierarchical\napproximation and describe how to incorporate a variety o
f constraints (on area\, volume\, etc.). Finally\, we\nexplore how this ma
chinery might be applied to problems in mathematical visualization\, geome
tric modeling\,\nand geometry processing.\nJoint work with: Chris Yu\, Cal
eb Brakensiek\, Keenan Crane\nReferences\n[1] C. Yu\, C. Brakensiek\, H. S
chumacher\, and C. Keenan Repulsive Surfaces. ACM Trans. Graph.\, 40(6):1
–19\,\n2021.\n[2] C. Yu\, H. Schumacher\, and C. Keenan Repulsive Curves
. ACM Trans. Graph.\, 40(2):1-21\, 2021.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marta Zoppello (DISMA\, Politecnico di Torino)
DTSTART;VALUE=DATE-TIME:20220328T134000Z
DTEND;VALUE=DATE-TIME:20220328T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/65
DESCRIPTION:Title: N-link swimmers swimming alone or in pairs\nby Marta Zoppello (DI
SMA\, Politecnico di Torino) as part of Nečas Seminar on Continuum Mechan
ics\n\n\nAbstract\nThis talk presents two models of swimmers immersed in a
low Reynolds number fluid\,\nboth of them involving the so-called N -link
swimmer. The first one studies the 3-dimensional N-link swimmer swimming
alone [1]\, the second focuses on two planar 2-link swimmers\nswimming tog
ether [2]. Both models rely on Resistive Force Theory\, which is a good ap
proximation of hydrodynamic forces at low Reynolds number for slender swim
mers and allows us to cast the equations of motion as ODEs. These equation
s can be seen as control systems\nwhere the controls are the velocity of d
eformation of the swimmers.\nWe prove that the 3 dimensional N -link swimm
er is fully controllable and we show the existence of optimal controls for
some cost functionals. Regarding the coupled swimmers\, even\nif\, taken
singularly\, they are non-controllable units (because of Purcell’s celeb
rated Scallop Theorem)\, we prove that taking into account the hydrodynami
c interaction they can achieve a net motion after a periodic sequence of s
hape changes. Moreover\, under suitable\napproximations\, we are able to o
ptimize the displacement.\n\n\n[1] R. Marchello\, M\, Morandotti\, H. Shum
\, M. Zoppello.\nThe N -link swimmer in three dimensions: controllability
and optimality results.\nAccepted for publication in Acta Applicandae Math
ematicae (2022)\n\n\n[2] M. Zoppello\, M. Morandotti\, H. Gadˆelha.\nCont
rolling non-controllable scallops.\nSubmitted.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:summer break
DTSTART;VALUE=DATE-TIME:20220523T134000Z
DTEND;VALUE=DATE-TIME:20220523T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/67
DESCRIPTION:by summer break as part of Nečas Seminar on Continuum Mechani
cs\n\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bangwei She (Inst. of Mathematics\, Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20220321T144000Z
DTEND;VALUE=DATE-TIME:20220321T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/68
DESCRIPTION:Title: On convergence of numerical solutions for the compressible MHD system
\nby Bangwei She (Inst. of Mathematics\, Czech Academy of Sciences) as
part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nWe study a g
eneral convergence theory for the analysis of numerical\n solutions to a m
agnetohydrodynamic system describing the time\n evolution of compressible\
, viscous\, electrically conducting fluids.\n \n First\, we introduce the
concept of consistent approximation mimicking\n the density positivity\, e
nergy stability\, and consistency of a\n suitable numerical approximation.
Further\, we introduce the concept of\n dissipative weak solution\, which
can be obtained as the weak limit of\n the consistent approximation. Here
\, by “dissipative" we mean that\n the energy inequality contains energy
defects that control the\n oscillations in the momentum equation.\n \n Ne
xt\, by using the relative energy functional\, we prove the\n dissipative
weak-strong uniqueness principle\, meaning that a\n dissipative weak solut
ion coincides with a classical solution of the\n same problem as long as t
he latter exists. This indicates that a\n consistent approximation converg
es unconditionally to the classical\n solution. As a summary\, we built a
nonlinear variant of the Lax\n equivalence theory for the compressible MHD
system.\n \n Finally\, to show the application of the convergence theory\
, we propose\n two numerical methods. We show that the numerical solutions
preserve\n the positivity of density and stability of the total energy. T
hen by\n using the a priori estimates derived from the energy estimates we
\n prove that the numerical methods are consistent. Consequently\, our\n n
umerical methods belong to the class of consistent approximation.\n Applyi
ng the prebuilt convergence theory\, we conclude that the\n solutions of o
ur numerical methods converge to i) the dissipative\n weak solution\; ii)
the classical solution as long as the classical\n solution exists. As a b
yproduct of the first convergence\, we prove the\n global in-time existenc
e of the dissipative weak solution.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Barbora Benešová (Charles University)
DTSTART;VALUE=DATE-TIME:20220425T134000Z
DTEND;VALUE=DATE-TIME:20220425T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/69
DESCRIPTION:Title: A model for polycrystalline Ni-Ti shape-memory alloys including plast
icity\nby Barbora Benešová (Charles University) as part of Nečas Se
minar on Continuum Mechanics\n\n\nAbstract\nIn this talk\, I will discuss
the interplay between the martensitic transformation and the plastic defor
mation in polycrystalline NiTi- alloys. I will then propose a phenomenolog
ical\, macroscopic model capturing both effects within the generalized sta
ndard materials modelling framework. Special attention will be paid to dis
tinguishing dependent and independent processes and their accurate modelli
ng. This is a joint work with Miroslav Frost\, Martin Kružík\, Petr Sedl
ák and Hanuš Seiner.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rufat Badal (University of Erlangen)
DTSTART;VALUE=DATE-TIME:20220214T144000Z
DTEND;VALUE=DATE-TIME:20220214T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/70
DESCRIPTION:Title: Nonlinear and Linearized Models in Thermoviscoelasticity\nby Rufa
t Badal (University of Erlangen) as part of Nečas Seminar on Continuum Me
chanics\n\n\nAbstract\nWe consider a quasistatic nonlinear model in thermo
viscoelasticity at a finite-strain setting in the Kelvin’s-Voigt’s rhe
ology where both the elastic and viscous stress tensors comply with the pr
inciple of frame indifference under rotations. The force balance is formul
ated in the reference configuration by resorting to the concept of nonsimp
le materials whereas the heat transfer equation is modeled by the Fourier
law in the deformed configurations. Weak solutions are obtained by means o
f a staggered in-time discretization where the deformation and the tempera
ture are updated alternatingly. Our result refines a recent work by Mielke
& Roubíček [1] since our approximation does not require any regularizat
ion of the viscosity term. Afterwards\, we focus on the case of deformatio
ns near the identity and small temperatures\, and we show by a rigorous li
nearization procedure that weak solutions of the nonlinear system converge
in a suitable sense to solutions of a system in linearized thermoviscoela
sticity. The same property holds for time-discrete approximations and we p
rovide a corresponding commutativity result.\n\n[1] Mielke A.\, Roubíček
T.: Thermoviscoelasticity in Kelvin-Voigt rheology at large strains. (202
0)\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michele Ruggeri (University of Strathclyde)
DTSTART;VALUE=DATE-TIME:20220314T144000Z
DTEND;VALUE=DATE-TIME:20220314T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/71
DESCRIPTION:Title: The Landau-Lifshitz-Gilbert equation with Dzyaloshinki-Moriya interac
tion: numerical aspects\nby Michele Ruggeri (University of Strathclyde
) as part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nThe talk
will be split into two parts.\nIn the first one\, we discuss the numerica
l approximation of the Landau-Lifshitz-Gilbert equation\n(LLG) for the cas
e in which the energy (and\, hence\, the effective field appearing in LLG)
includes\nthe Dzyaloshinki-Moriya interaction (DMI)\, the fundamental ing
redient for the enucleation and stability\nof chiral magnetic skyrmions. I
n the second part\, we discuss a limiting model for micromagnetic thin\nfi
lms in the presence of bulk DMI\, where we focus on the limiting behavior
of the magnetization\nas the thickness of the film goes to zero. We show t
hat the reduced model unveils some physics\nand discuss its practical impl
ications for computations. The results presented in the talk have been\nob
tained together with Giovanni Di Fratta (University of Naples Federico II)
\, Elisa Davoli\,\nCarl-Martin Pfeiler\, and Dirk Praetorius (TU Wien).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:---
DTSTART;VALUE=DATE-TIME:20220411T134000Z
DTEND;VALUE=DATE-TIME:20220411T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/72
DESCRIPTION:by --- as part of Nečas Seminar on Continuum Mechanics\n\nAbs
tract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rita Ferreira (King Abdullah University of Science and Technology)
DTSTART;VALUE=DATE-TIME:20221031T144000Z
DTEND;VALUE=DATE-TIME:20221031T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/73
DESCRIPTION:Title: Structural changes in nonlocal denoising models arising through bi-le
vel parameter learning\nby Rita Ferreira (King Abdullah University of
Science and Technology) as part of Nečas Seminar on Continuum Mechanics\n
\n\nAbstract\nIn this talk\, we will discuss a unified framework based on
bi-level optimization schemes to deal with parameter learning in the conte
xt of image processing. The goal is to identify the optimal regularizer wi
thin a family depending on a parameter in a general topological space. Of
particular interest is the non-compact parameter domains case\, which is r
elevant\, for instance\, when the commonly used box constraints are disreg
arded. To overcome this lack of compactness\, we propose a natural extensi
on of the upper-level functional to the closure of the parameter domain vi
a Gamma-convergence\, which captures possible structural changes in the re
construction model at the edge of the domain. Under two main assumptions\,
Mosco-convergence of the regularizers and uniqueness of minimizers of th
e lower-level problem\, we prove that the extension coincides with the rel
axation\, thus admitting minimizers that relate to the parameter optimizat
ion problem of interest. To conclude\, we apply this abstract framework to
investigate four practically relevant models in image denoising\, all fea
turing nonlocality\; moreover\, the associated families of regularizers ex
hibit qualitatively different parameter dependence\, describing a weight f
actor\, an amount of nonlocality\, an integrability exponent\, and a fract
ional order\, respectively. \nThis talk is based on a joint work with Elis
a Davoli\, Carolin Kreisbeck\, and Hidde Schönberger.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lennart Machill (University of Muenster\, Germany)
DTSTART;VALUE=DATE-TIME:20221010T134000Z
DTEND;VALUE=DATE-TIME:20221010T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/74
DESCRIPTION:Title: One-dimensional viscoelastic von Kármán theories\nby Lennart Ma
chill (University of Muenster\, Germany) as part of Nečas Seminar on Cont
inuum Mechanics\n\n\nAbstract\nWe derive an effective one-dimensional limi
t from a three-dimensional Kelvin-Voigt model for viscoelastic thin-walled
beams\, in which the elastic and the viscous stress tensor comply with a
frame-indifference principle. The limiting system of equations comprises s
tretching\, bending\, and twisting both in the elastic and the viscous str
ess. It coincides with the model already identified via [Friedrich-Kruží
k '20] and [Friedrich-Machill '22] by a successive dimension reduction\, f
irst from 3D to a 2D theory for von Kármán plates and then from 2D to a
1D theory for ribbons. Our arguments rely on the static Gamma-convergence
in [Freddi-Mora-Paroni '13]\, on the abstract theory of metric gradient fl
ows\, and on evolutionary Gamma-convergence by Sandier and Serfaty.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Elvira Zappale (University of Rome - I\, Sapienza)
DTSTART;VALUE=DATE-TIME:20221121T144000Z
DTEND;VALUE=DATE-TIME:20221121T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/75
DESCRIPTION:Title: Variational formulation for hierarchies of structured deformations\nby Elvira Zappale (University of Rome - I\, Sapienza) as part of Nečas
Seminar on Continuum Mechanics\n\n\nAbstract\nThe mechanical theory of fi
rst order structured deformations formulated in [2] enriches the purely ma
croscopic field theory of non-linear elasticity by taking into account the
effects of disarrangements that occur at a single submacroscopic level. I
n [1] a variational formulation for this theory has been successfully prov
ided in the context of special fields of bounded variation.\nTaking into a
ccount that many natural and man-made physical systems have a rich enough
geometrical structure to permit the identification of hierarchies consisti
ng of more than one physically meaningful submacroscopic level\, the mecha
nical theory of structured deformations has been enriched in [3]. This ta
lk aims at presenting a variational framework of these latter theoretical
settings.\n\n\nReferences:\n\n[1] R. Choksi and I. Fonseca: Bulk and inter
facial energy densities for structured deformations of continua. Arch. Rat
ional Mech. Anal. 138 (1997)\, 37-103.\n\n\n[2] G. Del Piero and D. -R. Ow
en: Structured deformations of continua: Arch. Ration. Mech. Anal. 124 (19
93)\, 99-155.\n\n[3] L. Deseri and D. R. Owen: Elasticity with Hierarchica
l Disarrangements: A Field Theory That Admits Slips and Separations at Mul
tiple Submacroscopic Levels: J.of Elasticity Vol- 135 (2019) Issue 1-2\, 1
49-180.\n\nJoint project with Ana Cristina Barroso\, José Matias\, Marco
Morandotti & David Owen\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martin Horák (Faculty of Civil Engineering\, CTU\, ÚTIA AVČR)
DTSTART;VALUE=DATE-TIME:20221003T134000Z
DTEND;VALUE=DATE-TIME:20221003T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/76
DESCRIPTION:Title: Efficient formulation of a two-dimensional geometrically exact Bernou
lli beam\nby Martin Horák (Faculty of Civil Engineering\, CTU\, ÚTI
A AVČR) as part of Nečas Seminar on Continuum Mechanics\n\nLecture held
in K3 Karlin\, Sokolovska 83\, Praha 8.\n\nAbstract\nIn this talk\, I will
focus on a two-dimensional geometrically exact formulation of a Bernoulli
beam.\nThe formulation is based on the integrated form of equilibrium equ
ations\, which are combined with the\nkinematic equations and generalized
material equations\, leading to a set of three first-order differential\ne
quations. These equations are then discretized by finite differences and t
he boundary value problem is\nconverted into an initial value problem usin
g a technique inspired by the shooting method. The accuracy of\nthe numeri
cal approximation is conveniently increased by refining the integration sc
heme on the element\nlevel while the number of global degrees of freedom i
s kept constant\, which leads to high computational\nefficiency. The eleme
nt has been implemented into an open-source finite element code. I will sh
ow a\nfavorable comparison with standard beam elements formulated in the f
inite-strain framework and with\nanalytical solutions. Several extensions
of the proposed approach\, including curved initial geometry\, follower pr
essure load\, and beam-to-beam contact will be also discussed. This is jo
int work with M. Jirásek and E. La Malfa Ribolla.\n\n\nREFERENCES\n\n\n[1
] Jirásek\, M.\,La Malfa Ribolla\, E.\, and Horák\, M. Efficient finite
difference formulation of a ge-ometrically nonlinear beam element. Interna
tional Journal for Numerical Methods in Engineering\,(2021) 122:7013–705
3.\n\n\n[2] Horák\, M.\, La Malfa Ribolla\, E.\, and Jirásek\, M. Effici
ent formulation of a two-noded geometrically exact curved beam element. In
ternational Journal for Numerical Methods in Engineering\, (2022)\, accept
ed for publication.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bohumír Bastl (University of West Bohemia)
DTSTART;VALUE=DATE-TIME:20221024T134000Z
DTEND;VALUE=DATE-TIME:20221024T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/77
DESCRIPTION:Title: Numerical simulation of incompressible fluid flow with the help of is
ogeometric analysis\nby Bohumír Bastl (University of West Bohemia) as
part of Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nIsogeometric
analysis is a relatively recently introduced concept for numerical\nsolvi
ng of partial differential equations which bridges the gap between\ngeomet
ric modelling and numerical simulation/analysis.\n\nIn this talk\, the iso
geometric analysis is used for numerical simulation of\nincompressible flu
id flow. We give an overview of the method which shares many\nfeatures wit
h Finite Element Method\, but different meshes and basis functions\nalso l
ead to significant differences. We present advantages and drawbacks of the
\nmethod which we have encountered during development of incompressible tu
rbulent\nflow solver and we focus on our results concerning isogeometric m
esh generation\,\nstabilization methods and solving systems of linear equa
tions in this context.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:John Simon (Institute of Mathematics\, Czech Academy of Sciences)
DTSTART;VALUE=DATE-TIME:20221114T144000Z
DTEND;VALUE=DATE-TIME:20221114T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/78
DESCRIPTION:Title: A NAIVE FORMULATION OF MAXIMIZING THE COMPUTATIONAL CAPABILITY OF THE
TWIN VORTEX COMPUTER VIA SHAPE OPTIMIZATION\nby John Simon (Institute
of Mathematics\, Czech Academy of Sciences) as part of Nečas Seminar on
Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics a
nd Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\n
Physical reservoir computing is a new computational paradigm based on recu
rrent neural networks\nwhere instead of optimizing nodal connection of the
internal network\, one gets to utilize the nonlinear behavior of\nphysica
l systems and gets to focus on optimizing a minimal number parameters. In
2021\, Goto et al [1] investigated\na physical reservoir computer in the c
ontext of a flow past a cylinder and shown that the computer’s computati
onal\ncapability is maximized at the bifurcation point between the generat
ion of twin vortex and the onset of Karman vortex.\nIn this exposition\, t
he authors illustrated how the the dynamics of twin vortex affects the abi
lity of the computer to\naccomplish certain tasks. In particular\, they ha
ve shown that the length of the twin vortex is directly proportional to\nt
he performance.\nIn this talk\, a shape optimization problem that aims to
increase the said capability will be presented. The op-\ntimization proble
m is a naive formulation by maximizing two types of functional which has b
een historically used a\nquantifiers of vortex\, namely\, the L2-norm of t
he curl of the velocity and the positivity of the determinant of the veloc
ity\ngradient. The optimization problem is regularized by a perimeter func
tional which acts as a Tikhonov regularizer. A\nvolume constraint is also
imposed\, which — together with the regularizer — prevents possible to
pological changes in\nthe domain. The analysis of this problem includes ex
istence analysis of the governing state\, establishing the existence\nof s
hape solutions\, and sensitivity of the objective functional with respect
to domain perturbation. We shall then utilize\nthe results of the sensitiv
ity analysis to a gradient descent-type algorithm for numerical illustrati
ons.\n\n[1] K. Goto\, K. Nakajima\, and H. Notsu\, Twin vortex computer in
fluid flow\, New J. Phys.\, 23 (2021)\, p. 063051\,\nhttps://doi.org/doi.
org/10.1088/1367-2630/ac024d.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jiří Mikyška (Faculty of Nuclear Sciences and Physical Engineer
ing\, Czech Tech. University)
DTSTART;VALUE=DATE-TIME:20221017T134000Z
DTEND;VALUE=DATE-TIME:20221017T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/79
DESCRIPTION:Title: An alternative model of multicomponent diffusion based on a combinati
on of the Maxwell-Stefan theory and continuum mechanics.\nby Jiří Mi
kyška (Faculty of Nuclear Sciences and Physical Engineering\, Czech Tech.
University) as part of Nečas Seminar on Continuum Mechanics\n\nLecture h
eld in Room K3\, Faculty of Mathematics and Physics\, Charles University\
, Sokolovská 83 Prague 8..\n\nAbstract\nI will present a theory of multi
component mixtures that do not employ any splitting of component fluxes\ni
nto convective and diffusive parts. Instead\, momentum balance is formulat
ed individually for each\ncomponent in which both 1) viscous friction with
in a component\, and 2) momentum exchange among different\ncomponents\, ar
e taken into account. While viscous friction is described using the Newton
ian stress\ntensor\, the Maxwell-Stefan theory is used to describe the mom
entum exchange among different components.\nWhen the viscosity is neglecte
d\, the model of an ideal mixture of ideal gases leads to a hyperbolic sys
tem of\nconservation laws. For the non-ideal mixtures\, we obtain the firs
t-order system in a non-conservative form.\nA simplified version of the mo
del is discretized using a combination of the finite volume method and the
\nmixed-hybrid finite element method. Numerical examples are provided to s
how the typical behavior of the\nsolution of the model equations.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dallas Albritton (Princeton University)
DTSTART;VALUE=DATE-TIME:20221205T144000Z
DTEND;VALUE=DATE-TIME:20221205T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/80
DESCRIPTION:Title: Non-uniqueness of Leray solutions to the forced Navier-Stokes equat
ions\nby Dallas Albritton (Princeton University) as part of Nečas Sem
inar on Continuum Mechanics\n\nLecture held in Institute of Mathematics\,
Žitná 25\, Praha 1\, library.\n\nAbstract\nIn a seminal work\, Leray de
monstrated the existence of\nglobal weak solutions to the Navier-Stokes eq
uations in three\ndimensions. Are Leray's solutions unique? This is a fund
amental\nquestion in mathematical hydrodynamics\, which we answer in the\n
negative within the `forced' category\, by exhibiting two distinct\nLeray
solutions with zero initial velocity and identical body force.\n\nThis is
joint work with Elia Brué and Maria Colombo.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20230109T144000Z
DTEND;VALUE=DATE-TIME:20230109T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/81
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20230116T144000Z
DTEND;VALUE=DATE-TIME:20230116T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/82
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20230123T144000Z
DTEND;VALUE=DATE-TIME:20230123T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/83
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20230130T144000Z
DTEND;VALUE=DATE-TIME:20230130T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/84
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semester break
DTSTART;VALUE=DATE-TIME:20230206T144000Z
DTEND;VALUE=DATE-TIME:20230206T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/85
DESCRIPTION:by semester break as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cy Maor (Hebrew University of Jerusalem)
DTSTART;VALUE=DATE-TIME:20230320T144000Z
DTEND;VALUE=DATE-TIME:20230320T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/86
DESCRIPTION:Title: Non-Euclidean elasticity: shape transitions in non-Euclidean ribbons<
/a>\nby Cy Maor (Hebrew University of Jerusalem) as part of Nečas Seminar
on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathemati
cs and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstra
ct\nMany bodies in nature that undergo inhomogeneous growth/shrinkage beco
me "pre-strained"\; that is\, they are stressed even in the absence of ext
ernal forces. They are typically modeled by having an intrinsic non-flat m
etric\, giving rise to non-Euclidean elasticity.\nOf particular interest a
re thin bodies: shell-like\, rod-like or ribbon-like bodies (e.g.\, leaves
or supramolecular assemblies)\, which exhibit interesting energy-driven p
atterns. In this talk I will describe the model of non-Euclidean elasticit
y\, and then focus on thin bodies\, the relations between their intrinsic
curvature and their elastic behavior\, and specifically on shape transitio
ns in non-Euclidean ribbons.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Easter Monday
DTSTART;VALUE=DATE-TIME:20230410T134000Z
DTEND;VALUE=DATE-TIME:20230410T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/87
DESCRIPTION:by Easter Monday as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Holiday
DTSTART;VALUE=DATE-TIME:20230501T134000Z
DTEND;VALUE=DATE-TIME:20230501T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/88
DESCRIPTION:by Holiday as part of Nečas Seminar on Continuum Mechanics\n\
nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles U
niversity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Holiday
DTSTART;VALUE=DATE-TIME:20230508T134000Z
DTEND;VALUE=DATE-TIME:20230508T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/89
DESCRIPTION:by Holiday as part of Nečas Seminar on Continuum Mechanics\n\
nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles U
niversity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Sváček (Faculty of Mechanical Engineering\, CTU)
DTSTART;VALUE=DATE-TIME:20230522T134000Z
DTEND;VALUE=DATE-TIME:20230522T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/90
DESCRIPTION:Title: On Application of Finite Element Method for Fluid-Structure-Acoustic
Interactions Related to Human Phonation Process\nby Petr Sváček (Fac
ulty of Mechanical Engineering\, CTU) as part of Nečas Seminar on Continu
um Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Phys
ics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nHuman v
oice is created by a complex process consisting of mutual\ninteractions of
flowing air\, vibrating vocal folds and the sound propagation\nthrough th
e vocal tract. The fundamental sound is created by the mutual\ninteraction
of the flowing air with vibrations of vocal folds(VFs). The\narising fun
damental sound is enriched by aeroacoustic sound sources and\npropagated t
hrough the vocal tract. In this talk\, mathematical models of a\nsimplifie
d fluid-structure-acoustic interaction problem shall be\,\nnumerically dis
cretized and numerical results will be presented. In\nparticular the defor
mation of an elastic body representing the model of\nvocal folds will be c
onsidered in the interaction with the complex fluid\nflow and aeroacoustic
s. In particular the attention will be paid to several\nimportant issues o
f such a modelling as the inclusion of the VFs contact\,\nchoice of suitab
le boundary conditions\, the influence of pre-stressed vocal\nfold on the
fundamental frequency\, etc. For the flow model the realization\nof the va
riational multiscale method is discussed. The numerical\napproximation of
the problem is presented and numerical results are shown.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xmas
DTSTART;VALUE=DATE-TIME:20221226T144000Z
DTEND;VALUE=DATE-TIME:20221226T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/91
DESCRIPTION:Title: no talk\nby Xmas as part of Nečas Seminar on Continuum Mechanics
\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charle
s University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabriel Pathó (Dlubal Software CS)
DTSTART;VALUE=DATE-TIME:20221107T144000Z
DTEND;VALUE=DATE-TIME:20221107T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/92
DESCRIPTION:Title: Constitutive modelling of masonry for civil engineering\nby Gabri
el Pathó (Dlubal Software CS) as part of Nečas Seminar on Continuum Mech
anics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, C
harles University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe discuss the
macroscale modeling of masonry consisting of brick and mortar as a brittl
e material and its implementation in the commercial software RFEM 6 which
is convenient for practical civil engineers and complies with both Eurocod
e 6 and available test data.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:cancelled
DTSTART;VALUE=DATE-TIME:20221128T144000Z
DTEND;VALUE=DATE-TIME:20221128T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/93
DESCRIPTION:Title: seminar is cancelled\nby cancelled as part of Nečas Seminar on C
ontinuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics an
d Physics\, Charles University\, Sokolovská 83 Prague 8..\nAbstract: TBA
\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Růžička (University of Freiburg)
DTSTART;VALUE=DATE-TIME:20221205T161000Z
DTEND;VALUE=DATE-TIME:20221205T171000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/94
DESCRIPTION:Title: Existence proofs for pseudomonotone parabolic problems\nby Michae
l Růžička (University of Freiburg) as part of Nečas Seminar on Continu
um Mechanics\n\nLecture held in Institute of Mathematics\, Žitná 25\, P
raha 1\, library.\n\nAbstract\nIn the talk we discuss nonlinear parabolic
problems which \ncontain a pseudomonotone operator. A new notion of Bochne
r pseudomonotonicity is introduced and \napplied. Extensions to quasi non-
conforming and non-conforming Bochner pseudomonotonicity yield\nconvergen
ce proofs for fully discrete Rothe–Galerkin schemes in the framework of
discretely divergence free FE and DG methods.\n\nReferences\n[1] E. Bauml
e and M. Růžička: Note on the existence theory for evolution \nequation
s with pseudomonotone operators\, Ric. Mat.\, 2017.\n\n[2] S. Bartels\, M.
Růžička: Convergence of fully discrete implicit and \nsemi-implicit ap
proximations of singular parabolic equations\, SIAM J. Numer. Anal.\, 2020
.\n\n[3] A. Kaltenbach\, M. Růžička: Note on the existence theory for \
npseudo-monotone evolution problems\, J. Evol. Equ.\, 2021.\n\n[4] L.C. Be
rselli\, A. Kaltenbach\, M. Růžička: Analysis of fully \ndiscrete\, qua
si non-conforming approximations of evolution equations and applications\,
Math. Models \nMethods Appl. Sci.\, 2021.\n\n[5] A. Kaltenbach\, M. Růž
ička: Analysis of fully discrete\, non-conforming approximation of evolu
tion equations and applications\, in preparation\, 2022.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sourav Mitra (Institute of Mathematics\, Czech Academy of Sciences
)
DTSTART;VALUE=DATE-TIME:20221212T144000Z
DTEND;VALUE=DATE-TIME:20221212T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/95
DESCRIPTION:Title: Existence of a weak solution for a compressible multicomponent fluid-
structure interaction problem\nby Sourav Mitra (Institute of Mathemati
cs\, Czech Academy of Sciences) as part of Nečas Seminar on Continuum Mec
hanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\,
Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nI will speak
about our recent work on the analysis of a system of PDEs governing the in
teraction between two compressible mutually noninteracting fluids and a sh
ell of Koiter type encompassing a time-dependent 3D domain filled by the f
luids. The dynamics of the fluids is modeled by compressible\nNavier-Stoke
s equations with a physically realistic pressure depending on the densitie
s of both fluids. The shell constitutes the boundary of the fluid domain\,
and it possesses a non-linear\, non-convex Koiter energy (of a quite gene
ral form). We are interested in the existence of a weak solution to the sy
stem\nuntil the time-dependent boundary approaches a self-intersection. We
first prove a global existence result (until a degeneracy occurs) when th
e adiabatic exponents solve max{γ\, β} > 2 and min{γ\, β} > 0\, and fu
rther\, the densities are comparable. Next\, with a slightly extra regular
ity assumption on the\ninitial structural displacement\, we extend our glo
bal existence result to the case max{γ\, β} ≥ 2 and min{γ\, β} > 0.\
nIn the first part of the talk\, I will try to introduce the classical the
ory on the existence of weak solutions for compressible mono-fluid models.
Next\, I will talk about our work on the multi-component FSI problem. Thi
s is joint work with M. Kalousek and Š. Nečasová.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nilasis Chaudhuri (Imperial College London)
DTSTART;VALUE=DATE-TIME:20221219T144000Z
DTEND;VALUE=DATE-TIME:20221219T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/96
DESCRIPTION:Title: Navier--Stokes--Fourier system with Dirichlet boundary conditions for
temperature\nby Nilasis Chaudhuri (Imperial College London) as part o
f Nečas Seminar on Continuum Mechanics\n\n\nAbstract\nIn this talk\, we c
onsider the Navier--Stokes--Fourier system\,\ndescribing the motion of a c
ompressible\, viscous\, and heat conducting\nfluid in a bounded domain $\\
Omega \\subset R^d$\, $d =2\,3$\, with general\nnon-homogeneous Dirichlet
boundary conditions for the absolute\ntemperature. We introduce a new conc
ept of weak solution based on the\nsatisfaction of the entropy inequality
together with a balance law for\nthe ballistic energy. We show the existen
ce of global-in-time weak\nsolutions\, as well as the weak--strong uniquen
ess principle.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jiří Outrata (Czech Academy of Sciences\, Institute of Informati
on Theory and Automation)
DTSTART;VALUE=DATE-TIME:20230102T144000Z
DTEND;VALUE=DATE-TIME:20230102T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/97
DESCRIPTION:Title: On the application of the SCD semismooth* Newton method to variationa
l inequalities of the second kind\nby Jiří Outrata (Czech Academy of
Sciences\, Institute of Information Theory and Automation) as part of Ne
čas Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty
of Mathematics and Physics\, Charles University\, Sokolovská 83 Prague 8
..\n\nAbstract\nThe first part of the lecture deals with a description of
the SCD (subspace containing\nderivative) mappings and the SCD semismooth*
Newton method for the solution of general\ninclusions. This method is the
n applied to a class of variational inequalities of the second\nkind. As a
result\, one obtains an implementable algorithm exhibiting a locally supe
rlinear\nconvergence. Finally\, we demonstrate the efficiency of a globali
zed version of this method\nvia a Cournot-Nash equilibrium in which the ob
jectives of the players (firms) are nonsmooth\ndue to the presence of the
so-called cost of change. The problem is modeled as a variational\ninequal
ity of the second kind and\, to test the performance of the applied method
\, one admits\nreally large numbers of players and produced commodities.\n
Joint work with: Helmut Gfrerer and Jan Valdman.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Malte Kampschulte (Faculty of Mathematics and Physics\, Charles Un
iversity)
DTSTART;VALUE=DATE-TIME:20230213T144000Z
DTEND;VALUE=DATE-TIME:20230213T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/98
DESCRIPTION:Title: Self-contact for inertial problems in continuum mechanics\nby Mal
te Kampschulte (Faculty of Mathematics and Physics\, Charles University) a
s part of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3
\, Faculty of Mathematics and Physics\, Charles University\, Sokolovská
83 Prague 8..\n\nAbstract\nThere are many theories about elastic collisio
ns of solids and the resulting inertial evolution. What unifies most of th
em is that they involve some phenomenological assumption. The aim of this
talk is to present a recent result which shows that for the self-collision
of elastic bulk solids\, it is in fact sufficient to consider matter non-
interpenetration. Based only on this\, we are able to derive existence of
weak solutions including contact with obstacles and self-contact for arbit
rary large times and for large deformations. Additionally we are able to p
recisely characterize the contact forces as a vector-valued measure. This
is based on joint works with A. Češík\, and G. Gravina.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivan Gudoshnikov (Institute of Mathematics\, Czech Academy of Scie
nces)
DTSTART;VALUE=DATE-TIME:20230220T144000Z
DTEND;VALUE=DATE-TIME:20230220T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/99
DESCRIPTION:Title: Elastoplasticity with softening in spring network models: a state-de
pendent sweeping process approach\nby Ivan Gudoshnikov (Institute of M
athematics\, Czech Academy of Sciences) as part of Nečas Seminar on Conti
nuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Ph
ysics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nSofte
ning plasticity and Gurson model of damage in particular lead to ill-posed
mathematical\nproblems due to the loss of monotonicity. Multiple co-exist
ing solutions are possible when softening\nelements are coupled together\,
and solutions cannot be continued beyond the point of complete\nfailure o
f a material. Moreover\, spatially continuous models with softening suffer
from localization\nof strains and stresses to measure-zero submanifolds.\
nWe formulate a problem of quasistatic evolution of elasto-plastic spring
networks (Lattice Spring\nModels) with a plastic flow rule which describes
linear hardening\, linear softening and perfectly\nplastic springs in a u
niform manner. The fundamental kinematic and static characteristics of the
\nnetwork are described by the rigidity theory and structural mechanics.\n
To solve the evolution problem we convert it to a type of a differential q
uasi-variational inequality known as the state-dependent sweeping process.
We prove the existence of solution to the\nassociated time-stepping probl
em (implicit catch-up algorithm)\, and the estimates we obtain imply\nthe
existence of a solution to the (time-continuous) sweeping process.\nUsing
numerical simulations of regular grid-shaped networks with softening we de
monstrate\nthe development of non-symmetric shear bands. At the same time\
, in toy examples it is easy to\nanalytically derive multiple co-existing
solutions\, appearing in a bifurcation which happens when\nthe parameters
of the networks continuously change from hardening through perfect plastic
ity to\nsoftening.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pei Su (Charles University\, Faculty of Mathematics and Physics)
DTSTART;VALUE=DATE-TIME:20230227T144000Z
DTEND;VALUE=DATE-TIME:20230227T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/100
DESCRIPTION:Title: Asymptotic analysis of the system describing a small moving rigid bo
dy in viscous incompressible fluid\nby Pei Su (Charles University\, Fa
culty of Mathematics and Physics) as part of Nečas Seminar on Continuum M
echanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\
, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe consider
the interaction between a viscous incompressible fluid and a\nsmall rigid
body\, which is immersed in the fluid. The fluid is modeled by\nthe 3D Na
vier-Stokes equations. The motion of the body obeys the conservation of li
near and angular momentum. We assume that the density of the\nbody is cons
tant which is independent of the size of the body ε. Based on\nthe L\np
− L\nq\nestimate of the so-called fluid-structure semigroup\, we obtain
a\nuniform estimate for the velocity of the body. In particular\, we show
that\nthese estimates are ε-invariant. This help us to construct an appro
ximation\nsequence of the test functions of the fluid-body system. We prov
e that the solution of the fluid-body system\, in appropriate sense\, conv
erges to a solution\nof the Navier-Stokes equations as ε → 0.\nThis is
a joint work with Jiao He (Univerist´e Paris-Sud).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edoardo Mainini (University of Genoa)
DTSTART;VALUE=DATE-TIME:20230306T144000Z
DTEND;VALUE=DATE-TIME:20230306T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/101
DESCRIPTION:Title: Stability conditions for the linearization of pure traction problems
of finite elasticity.\nby Edoardo Mainini (University of Genoa) as pa
rt of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\,
Faculty of Mathematics and Physics\, Charles University\, Sokolovská 83
Prague 8..\n\nAbstract\nWe discuss the linearization of finite elasticity
by means of Gamma-convergence for the case of pure traction problems. For
hyperelastic bodies subject to equilibrated force fields\, the limit energ
y can be different from the global energy of linear elasticity subject to
the same force field. However\, under a suitable curl constraint\, we show
that the linear elastic equilibrium can be obtained as limit of local min
imizers of finite elasticity. This is joint work with Roberto Ognibene and
Danilo Percivale.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monika Balaszová (Facaulty of Mathematics and Physics\, Charles U
niversity)
DTSTART;VALUE=DATE-TIME:20230515T134000Z
DTEND;VALUE=DATE-TIME:20230515T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/102
DESCRIPTION:Title: Discontinuous Galerkin method for problems in time-depend domains
– theory and applications\nby Monika Balaszová (Facaulty of Mathema
tics and Physics\, Charles University) as part of Nečas Seminar on Contin
uum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Phy
sics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nMost o
f the theoretical mathematical results on the solvability and numerical an
alysis of nonstationary partial differential equations are obtained under
the assumption that a space domain is independent of time. However\, probl
ems in time-dependent domains are important in a number of areas of scienc
e and technology. This is particularly the case of fluid-structure interac
tion problems\, when the flow is solved in a domain deformed due to the co
upling with an elastic structure. There are various approaches to the solu
tion of problems in time-dependent domains\, a very popular technique is t
he arbitrary Lagrangian-Eulerian (ALE) method. In this talk we present an
ALE version of the space-time discontinuous Galerkin method\, which is bas
ed on piecewise polynomial approximations over finite element meshes\, in
general discontinuous on interfaces between neighbouring elements. We show
that the proposed method is numerically unconditionally stable and demons
trate its robustness on a numerical solution of the nonlinear elasticity b
enchmark problem. The developed method is also applied to the numerical si
mulation of air flow in a simplified model of human vocal tract and flow i
nduced vocal folds vibrations.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Florian Oschmann (Institute of Mathematics AS CR)
DTSTART;VALUE=DATE-TIME:20230313T144000Z
DTEND;VALUE=DATE-TIME:20230313T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/103
DESCRIPTION:Title: Some insides in homogenization of compressible Navier-Stokes equatio
ns\nby Florian Oschmann (Institute of Mathematics AS CR) as part of Ne
čas Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty
of Mathematics and Physics\, Charles University\, Sokolovská 83 Prague 8
..\n\nAbstract\nWe investigate the homogenization of the two- and\nthree-d
imensional unsteady compressible Navier-Stokes equations\, and\nshow (i) t
he convergence result for the 2D case\, and (ii) a better lower\nbound for
the adiabatic exponent occurring in the pressure law for the\n3D case. Th
e latter will be covered with two different proofs. Lastly\,\nwe briefly d
iscuss the optimality of the achieved bounds for the\nadiabatic exponent i
n terms of the underlying space-time dimension. This\nis joint work with
Šárka Nečasová (CAS) and Milan Pokorný\n(Charles University).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Morandotti (Politecnico di Torino)
DTSTART;VALUE=DATE-TIME:20230403T134000Z
DTEND;VALUE=DATE-TIME:20230403T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/104
DESCRIPTION:Title: Semi-discrete modeling of systems of disclinations and dislocations<
/a>\nby Marco Morandotti (Politecnico di Torino) as part of Nečas Seminar
on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathemati
cs and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstra
ct\nDisclinations in crystalline materials are point defects that are resp
onsible for rotational kinematic incompatibility. They are characterised b
y the so-called Frank angle\, measuring the severity of the lattice mismat
ch. In a two-dimensional medium under the assumption of plain strain\, the
Airy stress function can be used to translate the measure of incompatibil
ity into a fourth-order PDE with measure data. \n\nWe propose a variationa
l model for disclinations in two-dimensional materials by means of the cor
e-radius approach. Moreover\, we identify a good scaling regime in which w
e study the effective behaviour of dipoles of disclinations (of opposite s
igns)\, thus validating analytically the results obtained in [Eshelby\, 19
66]: a dipole of plane disclinations generates an edge dislocation with Bu
rgers vector perpendicular to the dipole axis. Finally\, we study the ener
gy of a system of a finite number of dipoles of disclinations and recover
the results of [Cermelli-Leoni\, 2005] for edge dislocations.\n\n \n\nThis
is work in collaboration with Pierluigi Cesana (Kyushu University) and Lu
cia De Luca (CNR Rome).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Franco Tomarelli (Politecnico di Milano)
DTSTART;VALUE=DATE-TIME:20230424T134000Z
DTEND;VALUE=DATE-TIME:20230424T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/105
DESCRIPTION:Title: Pure traction and Signorini problem between linear and finite elasti
city\nby Franco Tomarelli (Politecnico di Milano) as part of Nečas Se
minar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Math
ematics and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nA
bstract\nA limit elastic energy for pure traction problem is derived from
re-scaled nonlinear energies of a\nhyper-elastic material body subject to
an equilibrated force field.\nWe show that the strains of minimizing seque
nces associated to re-scaled nonlinear energies weakly\nconverge\, up to s
ubsequences\, to the strains of minimizers of a limit energy.\nThe limit e
nergy functional exhibits a gap that makes it different from the classical
linear elasticity\nfunctional. Nevertheless a suitable compatibility cond
ition entails the coincidence of related minima\nand minimizers\, hence th
e rigorous validation of linear elasticity. Strong violation of this condi
tion\nprovides a limit energy which is unbounded from below\, while a mild
violation may produce\nunboundedness of strains and a limit energy which
has infinitely many extra minimizers which are\nnot minimizers of standard
linear elastic energy. As a consequence\, a rigorous validation of linear
\nelasticity fails for compressive force fields that infringe such a compa
tibility condition.\nThis phenomenon has relevant consequences also on the
validation of the Signorini problem in\nlinear elasticity: there are load
s pushing the body against the obstacle\, but unfit for the geometry of\nt
he whole system body-obstacle\, so that the corresponding variational limi
t turns out to be different\nfrom the classical Signorini problem. However
\, if the force field acting on the body fulfils an\nappropriate geometric
admissibility condition\, we can show coincidence of related solutions.\n
The asymptotic analysis provides a sharp and rigorous variational justific
ation of the unilateral\nproblem in linear elasticity\, together with an a
ccurate analysis of the unilateral constraint.\nThese results were obtaine
d in a joint research with Francesco Maddalena (Politecnico di Bari) and\n
Danilo Percivale (Università di Genova).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manuel Friedrich (University of Erlangen)
DTSTART;VALUE=DATE-TIME:20230327T134000Z
DTEND;VALUE=DATE-TIME:20230327T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/106
DESCRIPTION:Title: Finite crystallization via stratification\nby Manuel Friedrich (
University of Erlangen) as part of Nečas Seminar on Continuum Mechanics\n
\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles
University\, Sokolovská 83 Prague 8..\n\nAbstract\nIn this talk\, I pres
ent a new technique to prove two-dimensional\ncrystallization results in t
he square lattice for finite particle\nsystems. We consider configurationa
l energies featuring two-body\nshort-ranged particle interactions and thre
e-body angular potentials\nfavoring bond-angles of the square lattice. To
each configuration\, we\nassociate its bond graph which is then suitably m
odified by identifying\nchains of successive atoms. This method\, called s
tratification\, reduces\nthe crystallization problem to a simple minimizat
ion that corresponds to\na proof via slicing of the isoperimetric inequali
ty in l1. Based on\njoint work with Leonard Kreutz.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Katerina Nik (University of Vienna)
DTSTART;VALUE=DATE-TIME:20230417T134000Z
DTEND;VALUE=DATE-TIME:20230417T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/107
DESCRIPTION:Title: Analysis of a three-dimensional model for MEMS with a hinged upper p
late\nby Katerina Nik (University of Vienna) as part of Nečas Seminar
on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathemati
cs and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstra
ct\nAn idealized electrostatic microelectromechanical system (MEMS) consis
ts of a rigid ground plate above which a thin elastic plate is suspended.
The elastic plate is assumed to be hinged on its boundary. Applying a volt
age difference between the two plates induces a Coulomb force that deforms
the elastic plate. The corresponding mathematical model couples a fourth-
order parabolic equation for the vertical deformation of the elastic plate
to the harmonic electrostatic potential in the free domain between the tw
o plates. In this talk\, I will present some recent results on local and g
lobal well-posedness of the model as well as on existence and non-existenc
e of stationary solutions.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Semester break
DTSTART;VALUE=DATE-TIME:20230529T134000Z
DTEND;VALUE=DATE-TIME:20230529T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/108
DESCRIPTION:Title: We'll go on in October 2023\nby Semester break as part of Nečas
Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of M
athematics and Physics\, Charles University\, Sokolovská 83 Prague 8..\n
Abstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semestr break
DTSTART;VALUE=DATE-TIME:20230904T134000Z
DTEND;VALUE=DATE-TIME:20230904T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/109
DESCRIPTION:by semestr break as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semestr break
DTSTART;VALUE=DATE-TIME:20230911T134000Z
DTEND;VALUE=DATE-TIME:20230911T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/110
DESCRIPTION:by semestr break as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semestr break
DTSTART;VALUE=DATE-TIME:20230918T134000Z
DTEND;VALUE=DATE-TIME:20230918T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/111
DESCRIPTION:by semestr break as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:semestr break
DTSTART;VALUE=DATE-TIME:20230925T134000Z
DTEND;VALUE=DATE-TIME:20230925T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/112
DESCRIPTION:by semestr break as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Angkana Rüland (University of Bonn)
DTSTART;VALUE=DATE-TIME:20231002T134000Z
DTEND;VALUE=DATE-TIME:20231002T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/113
DESCRIPTION:Title: Rigidity and Flexibility in the Modelling of Shape-Memory Alloys
\nby Angkana Rüland (University of Bonn) as part of Nečas Seminar on Con
tinuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and
Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nIn
the modelling of shape-memory alloys\, a striking dichotomy between rigid
and flexible behaviour emerges: On the one hand\, in many physically relev
ant settings\, exactly stress-free structures of sufficiently high regular
ity can be shown to satisfy the kinematic compatibility conditions given b
y the characteristics of the compatibility equations. The solutions are ri
gid. On the other hand\, when dropping these regularity conditions\, the m
ethod of convex integration shows that a plethora of wild\, irregular solu
tions exist which do not satisfy the kinematic conditions in general. Thes
e solutions can approximate a large class of boundary data and are thus fl
exible. In this talk\, I discuss an approach towards investigating this di
chotomy in more detail based on scaling laws. For a class of simplified mo
dels\, we show that the complexity of the microstructure is captured by th
ese scaling laws both in settings with displacement and with nucleation bo
undary conditions.\n\nThe talk is based on joint work with P. Cesana\, F.
Della Porta\, J. M. Taylor\, A. Tribuzio\, Ch. Zillinger\, B. Zwicknagl.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Illia Donhauzer (La Trobe University)
DTSTART;VALUE=DATE-TIME:20231009T134000Z
DTEND;VALUE=DATE-TIME:20231009T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/114
DESCRIPTION:Title: Limit theorems for multifractal products of random fields\nby
Illia Donhauzer (La Trobe University) as part of Nečas Seminar on Continu
um Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Phys
ics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nThe tal
k is about random functions with changing local regularity\n exponent (mul
tifractal processes and multifractal fields in multidimensional\n cases).
This type of random function has been observed in various areas\n includin
g communication systems\, precipitation fields\, econometrics\, and so\n o
n. The goal of this talk is to present new results in the modeling of\n mu
ltifractal random functions. One of the possible approaches to obtain\n mu
ltifractal random functions is as limits of multifractal products of\n ran
dom functions (roughly speaking\, integrals of infinite products of random
\n functions). In the talk\, I will show new results on the existence of t
hose\n limits in the spaces Lq as well as new results on the rate of conve
rgence.\n The developed methodology is also applied to multidimensional mu
ltifractal\n measures. Finally\, I will show a new class of examples of ge
ometric\n φ-sub-Gaussian random functions when the general assumptions ha
ve a simple\n form and can be expressed in terms of covariance functions o
nly.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kerrek Stinson (University of Bonn)
DTSTART;VALUE=DATE-TIME:20240108T144000Z
DTEND;VALUE=DATE-TIME:20240108T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/115
DESCRIPTION:Title: Regularity for minimizers of the Griffith fracture energy\nby Ke
rrek Stinson (University of Bonn) as part of Nečas Seminar on Continuum M
echanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\
, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nThe Griffit
h criterion says that the energy to crack a brittle\nelastic material is p
roportional to the length of the crack. Understanding\nthe regularity of m
inimizers requires unraveling the complex interplay of\nbulk (elastic) and
surface (crack) energies in the vectorial setting of\nlinearized frame in
difference. In dimension 2\, we prove that the crack of a\nminimizer is gi
ven by a $C^{1\,\\alpha}$ surface outside of a singular set of\npoints tha
t has dimension strictly less than 1\, analogous to results for the\nscala
r Mumford-Shah functional. Joint work with Manuel Friedrich (FAU) and\nCam
ille Labourie (UPS).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valentin Calisti (Institute of Mathematics\, Czech Academy of Scie
nces)
DTSTART;VALUE=DATE-TIME:20231030T144000Z
DTEND;VALUE=DATE-TIME:20231030T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/116
DESCRIPTION:Title: Minimization of blood damage induced by non-Newtonian fluid flows in
moving domains\nby Valentin Calisti (Institute of Mathematics\, Czech
Academy of Sciences) as part of Nečas Seminar on Continuum Mechanics\n\n
Lecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Un
iversity\, Sokolovská 83 Prague 8..\n\nAbstract\nMany engineering works
are interested in the parametric optimization of\nblood pumps to minimize
hemolysis (destruction of red blood cells).\nIn order to generalize this a
pproach\, we study the shape continuity of a\ncoupled system of PDEs model
ing blood flows and hemolysis evolution in\nmoving domains\, governed resp
ectively by generalized Navier-Stokes and\ntransport equations.\n\nFirst\,
the shape continuity of the blood flow solutions is shown. This\ndevelopm
ent\, which extends the one led in (Sokolowski\, Stebel\, Evol.\nEqu. Cont
rol Theory\, 2014) to the case of shear thinning fluids\, is\nbased on the
recent progress made in (Nägele\, Ružička\, J. Differential\nEquations
\, 2018)\, adapted to the present framework of a sequence of\nconverging m
oving domains.\n\nAfter calculating blood flows solutions\, the velocity a
nd stress fields\nare used as coefficients and r.h.s for the transport equ
ation governing\nthe evolution of the hemolysis rate. From this\, the shap
e continuity of\nthe hemolysis rate is also proved.\n\nFinally\, these res
ults allow to show the existence of minimum for a\nclass of shape optimiza
tion problems based on the minimization of the\nhemolysis rate\, in the fr
amework of moving domains.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:CANCELLED
DTSTART;VALUE=DATE-TIME:20231211T144000Z
DTEND;VALUE=DATE-TIME:20231211T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/117
DESCRIPTION:by CANCELLED as part of Nečas Seminar on Continuum Mechanics\
n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles
University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe discuss the stabi
lity of objective structures of interacting atoms that form a far-reaching
generalization of crystal lattices. To this end\, we use methods from har
monic analysis to set up a second derivative test of the configurational e
nergy at equilibria\, a key point being the identification of a carefully
chosen seminorm with respect to which coercivity is estimated. In particul
ar\, a novel discrete Korn-type inequality is established in the setting o
f objective structures. We also provide an efficient algorithm to check fo
r atomistic stability\, which we illustrate numerically for a general carb
on nanotube. (This is joint work with M. Steinbach\, Augsburg).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anastasia Molchanova (University of Vienna)
DTSTART;VALUE=DATE-TIME:20231204T144000Z
DTEND;VALUE=DATE-TIME:20231204T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/118
DESCRIPTION:Title: Variational Model of a Hyperelastic Capacitor\nby Anastasia Molc
hanova (University of Vienna) as part of Nečas Seminar on Continuum Mecha
nics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Ch
arles University\, Sokolovská 83 Prague 8..\n\nAbstract\nThis talk discu
sses an interplay between elastic deformations and electrostatic capacitan
ce for charged elastic materials. We consider a variational model\, where
electroelastic energy involves coupling elastic response and electrostatic
s using a capacitary term naturally defined in Eulerian coordinates. The e
nsuing electroelastic energy is then of mixed Lagrangian-Eulerian type. We
study the continuity properties of the capacitary terms under the converg
ence of the deformations and prove the existence of minimizers.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jiří Zeman (Faculty of Mathematics and Physics\, Charles Univers
ity)
DTSTART;VALUE=DATE-TIME:20231106T144000Z
DTEND;VALUE=DATE-TIME:20231106T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/119
DESCRIPTION:Title: Bending-torsion theories for elastic and brittle nanowires as Gamma-
limits of atomistic models\nby Jiří Zeman (Faculty of Mathematics an
d Physics\, Charles University) as part of Nečas Seminar on Continuum Mec
hanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\,
Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nNanotechnolog
y has ranked among paradigm-shifting and the fastest growing research area
s over the last 30 years. To benefit from the wide application prospects o
f engineered nanoworld objects\, it is important to study their mechanical
response\, which often differs from that of macroscopic bodies\, though (
because of size or structure effects for example). In particular\, there e
xist rod-like structures in nanoengineering which are long enough in one d
irection for continuum theories to be applicable\, but in the perpendicula
r direction\, they have a diameter on the scale of tens to hundreds of ato
ms. In this talk\, derivation of nonlinear continuum models for thin and u
ltrathin rods will be presented. We start from a 3D crystalline lattice wi
th short-range interactions and study simultaneous limits of vanishing rod
thickness and interatomic distance. Gamma-convergence especially yields a
novel theory for inextensible rods that undergo bending\, torsion\, and b
rittle fracture. New discrete and surface terms appear in the limiting ene
rgy functional\, whose fracture part is expressed by an implicit cell form
ula that covers different modes of fracture\, including (complete) cracks\
, folds and torsional cracks. Joint work with Bernd Schmidt (Augsburg).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefano Almi (University of Naples)
DTSTART;VALUE=DATE-TIME:20231127T144000Z
DTEND;VALUE=DATE-TIME:20231127T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/120
DESCRIPTION:Title: Strain gradient plasticity and multi-well potentials\nby Stefano
Almi (University of Naples) as part of Nečas Seminar on Continuum Mechan
ics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Cha
rles University\, Sokolovská 83 Prague 8..\n\nAbstract\nI will present a
strain-gradient plasticity model obtained as\n$\\Gamma$-limit of a nonlin
ear finite dislocation model characterised by\na multiple-well potential a
nd a singular perturbation term accounting\nfor the divergence of the stra
in field. The analysis builds upon a new\nquantitative rigidity estimate f
or incompatible fields in presence of a\nmultiwell elastic energy\, showin
g that the $L^{1^{*}}$-distance of a\nstrain field from a single well is c
ontrolled in terms of the\n$L^{1^{*}}$-distance from a finite set of wells
\, of curl $\\beta$\, and\nof ${\\rm div} \\beta$. This is a joint work wi
th Dario Reggiani (Scuola\nSuperiore Meridionale) and Francesco Solombrino
(University of Naples\nFederico II).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xmas
DTSTART;VALUE=DATE-TIME:20231225T144000Z
DTEND;VALUE=DATE-TIME:20231225T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/121
DESCRIPTION:by Xmas as part of Nečas Seminar on Continuum Mechanics\n\nLe
cture held in Room K3\, Faculty of Mathematics and Physics\, Charles Univ
ersity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Raffaele Grande (Czech Academy of Sciences\, Institute of Informat
ion Theory and Automation)
DTSTART;VALUE=DATE-TIME:20231023T134000Z
DTEND;VALUE=DATE-TIME:20231023T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/122
DESCRIPTION:Title: Stochastic control problems and a convergence result for horizontal
mean curvature flow\nby Raffaele Grande (Czech Academy of Sciences\, I
nstitute of Information Theory and Automation) as part of Nečas Seminar o
n Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics
and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract
\nThe evolution by horizontal mean curvature flow was broadly studied for
its applications in neurogeometry and in image processing (e.g. Citti-Sart
i model). It represents the contracting evolution of a hypersurface embedd
ed in a particular geometrical setting\, called sub-Riemannian geometry\,
in which only some curves (called horizontal curves) are admissible by def
inition. This may lead to the existence of some points of the hypersurface
\, called characteristic\, in which is not possible to define the so-calle
d horizontal normal. To avoid this problem\, it is possible to use the not
ion of Riemannian approximation of a sub-Riemannian geometry applied to th
e horizontal mean curvature flow.\n\nI will show the connection between th
e evolution of a generic hypersurface in this setting and the associated s
tochastic optimal control problem. Then\, I will show some results of asym
ptotic optimal controls in the Heisenberg group and use them to show later
a convergence result between the solutions of the approximated mean curva
ture flow and the horizontal ones. This is from some joint works with N. D
irr and F. Dragoni.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tomáš Bodnár (Faculty of Mechanical Engineering\, Czech Technic
al University)
DTSTART;VALUE=DATE-TIME:20231016T134000Z
DTEND;VALUE=DATE-TIME:20231016T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/123
DESCRIPTION:Title: On the estimation of blood hemolysis index from viscoelastic stretch
model\nby Tomáš Bodnár (Faculty of Mechanical Engineering\, Czech
Technical University) as part of Nečas Seminar on Continuum Mechanics\n\n
Lecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Un
iversity\, Sokolovská 83 Prague 8..\n\nAbstract\nThis contribution prese
nts an alternative way of estimating the blood damage\nhemolysis index usi
ng the viscoelastic stretch tensor. This tensor is obtained\nby solving a
set of coupled partial differential equations describing the\nrheology of
shear-thinning viscoelastic fluid. The main advantage of the chosen\nappro
ach is that the already calculated and known stretch tensor is just reused
\nand postprocessed to assess the local deformation of red blood cells\, t
hat can\nin certain cases lead to degradation of the cell membranes and co
nsequent\nrelease of hemoglobin. The algorithm of solving the viscoelastic
stretch tensor\nequations and hemolysis index postprocessing will be outl
ined and discussed in\ndetail. Some initial numerical simulations for an a
xisymmetric idealized\nstenosed blood vessel\, obtained using an in-house
finite-volume solver\, will be\npresented.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Bresciani (Department of Mathematics\, University of Erlange
n)
DTSTART;VALUE=DATE-TIME:20231113T144000Z
DTEND;VALUE=DATE-TIME:20231113T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/124
DESCRIPTION:Title: CANCELED\nby Marco Bresciani (Department of Mathematics\, Univer
sity of Erlangen) as part of Nečas Seminar on Continuum Mechanics\n\nLect
ure held in Room K3\, Faculty of Mathematics and Physics\, Charles Univer
sity\, Sokolovská 83 Prague 8..\n\nAbstract\nWe study a variational mode
l for ferromagnetic elastomers featuring a mixed Eulerian-Lagrangian formu
lation. The magnetic variable is defined on the deformed configuration\nin
the actual space and the saturation constraint involves the Jacobian dete
rminant of\ndeformations.\nFirst\, in the case for purely elastic material
s\, we discuss the existence of equilibrium\nconfigurations and we investi
gate the model under quasistatic evolution in the rate-independent setting
. Subsequently\, we address the extension of the existence theory for\nthe
static problem to a framework allowing for cavitation.\nThe talk is partl
y based on joint work with Manuel Friedrich (FAU Erlangen-Nuernberg)\nand
Carlos Mora-Corral (Universidad Autonoma de Madrid).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jaroslav Kruis (Department of Mechanics\, Faculty of Civil Enginee
ring\, Czech Technical University)
DTSTART;VALUE=DATE-TIME:20231120T144000Z
DTEND;VALUE=DATE-TIME:20231120T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/125
DESCRIPTION:Title: Hydro-thermo-mechanical simulation of deep geological repository of
radioactive waste\nby Jaroslav Kruis (Department of Mechanics\, Facult
y of Civil Engineering\, Czech Technical University) as part of Nečas Sem
inar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathe
matics and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAb
stract\nPossible variants of deep geological repository will be introduced
. Selected\nengineering problems connected with the deep repositories will
be summarized\nand the appropriate mathematical models and numerical meth
ods for their\nsolution will be described. The first problem is heat trans
fer caused by the\nradioactive waste in steel-based containers of length a
bout 5 meters. The\nsizes of studied domain are approximately one kilomete
r and the investigated\nperiod is thousands of years long. A combination o
f suitable numerical\nmethods has to be used in order to finish the numeri
cal simulations in\nreasonable time. The second problem is thermo-hydro-me
chanical (THM)\nanalysis of a system container-bentonite layer-surrounding
rock massif. It\nis based on the balance equation of momentum\, mass and
energy together with\nvarious constitutive relationships. The THM analysis
is formulated for 2D\nand 3D.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xmas
DTSTART;VALUE=DATE-TIME:20231218T144000Z
DTEND;VALUE=DATE-TIME:20231218T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/126
DESCRIPTION:by Xmas as part of Nečas Seminar on Continuum Mechanics\n\nLe
cture held in Room K3\, Faculty of Mathematics and Physics\, Charles Univ
ersity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:New Year
DTSTART;VALUE=DATE-TIME:20240101T144000Z
DTEND;VALUE=DATE-TIME:20240101T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/127
DESCRIPTION:by New Year as part of Nečas Seminar on Continuum Mechanics\n
\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles
University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Leon Happ (TU Wien)
DTSTART;VALUE=DATE-TIME:20240311T144000Z
DTEND;VALUE=DATE-TIME:20240311T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/128
DESCRIPTION:Title: Extension operators for homogenization that preserve target manifold
constraints\nby Leon Happ (TU Wien) as part of Nečas Seminar on Cont
inuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and P
hysics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nMoti
vated by homogenization problems in micro-magnetics and plasticity\, we st
udy the existence of extension operators for W^{1\,p} Sobolev maps on peri
odically perforated domains\, where the maps are only allowed to range in
some prescribed Riemannian manifold. For applications\, one demands that s
eparate L^p bounds for the extension and its gradient\, independent of the
scale of the perforations\, hold. We stress that the main novelty of our
work lies in the fact that all functions are subject to a manifold constra
ined in the target space. The challenge is then to find an extension opera
tor preserving this feature. It turns out that this is a problem sitting r
ight at the interface between analysis and algebraic topology.\n\nThe unco
nstrained case was famously treated in an influential paper by E. Acerbi\,
V. C. Piat\, G. Dal Maso\, and D. Percivale from 1992\, providing a posit
ive answer for all p except infinity. However\, as soon as one starts to i
nclude manifold constraints\, the existence problem of extensions becomes
highly sensitive towards the relation between p and d and calls for a case
differentiation. It can be shown that\, due to Sobolev embeddings\, for p
bigger or equal than d the question whether every Sobolev function on a p
erforated domain possesses an extension reduces to a similar question for
continuous functions. This is a problem well studied in algebraic topology
and\, in theory\, there are tools available to determine its answer.\n\nT
hese observations lead us to focus on the case that p is smaller than d (e
.g.\, in the physically relevant instance that p=2\, d=3). Then\, for p>1\
, we can indeed proof the existence of an extension operator as described
above\, and under the additional assumption that the target manifold is [p
-1] connected (where [] is the floor function)\, meaning that the first [p
-1] fundamental groups of N are trivial. The proof builds upon the already
alluded result by E. Acerbi\, V. C. Piat\, G. Dal Maso\, and D. Percivale
\, combining it with an appropriate retraction onto the target manifold\,
firstly suggested by R. Hardt and F.-H. Lin in 1987\, and originating agai
n from algebraic topology. It is important to note that the extension oper
ator will not be linear. Already the target manifold constraint is not com
patible with linearity. \n\nIn my talk\, I will put a special emphasis on
illuminating the [p-1]-connectedness condition that arises from the constr
uction of the retraction onto N. The same assumption is already well-known
in the context of the Sobolev functions between manifolds\, where\, for i
nstance\, it determines the surjectivity of the trace operator. This is on
ly one example of a deeper connection that I will unveil.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Morandotti (Politecnico di Torino)
DTSTART;VALUE=DATE-TIME:20240219T144000Z
DTEND;VALUE=DATE-TIME:20240219T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/129
DESCRIPTION:Title: From game theory to the control of multi-agent systems\nby Marco
Morandotti (Politecnico di Torino) as part of Nečas Seminar on Continuum
Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physic
s\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nMotivated
by the analysis of evolutive systems of agents with strategies\, we enric
h the structure of the celebrated replicator equation to include more real
istic scenarios suitable for game-theoretic applications. In this context\
, non-linear continuity equations arise to describe the evolution of the m
ean-field limit of such systems. Starting from simple cases\, we discuss m
ore sophisticated models\, which include the interplay between the evoluti
on of the position of the players and the evolution of their strategies\;
the addition of a control factor that models the presence of a policy make
r in multi-population dynamics\, together with the rise and fall of leader
ship\; the effects of an entropic regularisation in the system\, as well a
s that of fluctuations.\n\nWe present the derivation of these equations\,
together with some well-posedness results.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bernd Schmidt (University of Augsburg)
DTSTART;VALUE=DATE-TIME:20240226T144000Z
DTEND;VALUE=DATE-TIME:20240226T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/130
DESCRIPTION:Title: On the Stability of Objective Structures\nby Bernd Schmidt (Univ
ersity of Augsburg) as part of Nečas Seminar on Continuum Mechanics\n\nLe
cture held in Room K3\, Faculty of Mathematics and Physics\, Charles Univ
ersity\, Sokolovská 83 Prague 8..\n\nAbstract\nWe discuss the stability
of objective structures of interacting atoms that form a far reaching gene
ralization of crystal lattices. To this end\, we use methods from harmonic
analysis to set up a second derivative test of the configurational energy
at equilibria\, a key point being the identification of a carefully chose
n seminorm with respect to which coercivity is estimated. In particular\,
a novel discrete Korn type inequality is established in the setting of obj
ective structures. We also provide an efficient algorithm to check for ato
mistic stability which we illustrate numerically for a general carbon nano
tube. (This is joint work with M. Steinbach\, Augsburg)\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Bresciani (University of Erlangen)
DTSTART;VALUE=DATE-TIME:20240415T134000Z
DTEND;VALUE=DATE-TIME:20240415T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/131
DESCRIPTION:Title: Variational models with Eulerian-Lagrangian formulation allowing for
material failure\nby Marco Bresciani (University of Erlangen) as part
of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Fa
culty of Mathematics and Physics\, Charles University\, Sokolovská 83 Pr
ague 8..\n\nAbstract\nWe investigate the existence of minimizers of variat
ional models with Eulerian-Lagrangian\nformulations. Similar models arise
naturally in many multi-physics problems such as\nthe modeling of nematic
and ferromagnetic elastomers. We consider energy functionals\ndepending on
the deformation of a body\, defined on its reference configuration\, and
an\nEulerian map defined on the unknown deformed configuration in the actu
al space. Our\nexistence theory moves beyond the purely elastic setting an
d accounts for material failure\nby addressing free-discontinuity problems
where both deformations and Eulerian fields are\nallowed to jump. To do s
o\, we build upon the work of Henao and Mora-Corral regarding\nthe variati
onal modeling of cavitation and fracture in nonlinear elasticity. Two main
\nsettings are considered by modeling deformations as Sobolev and SBV -map
s\, respectively.\nThe regularity of Eulerian maps is specified in each of
these two settings according to the\ngeometric and topological properties
of the deformed configuration. Effectiveness and\nlimitations of the theo
ry are illustrated by means of explicit examples.\nThe talk is based on jo
int work with Manuel Friedrich (FAU Erlangen-Nuremberg) and\nCarlos Mora-C
orral (Universidad Autonoma de Madrid).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giovanni Fantuzzi (University of Erlangen)
DTSTART;VALUE=DATE-TIME:20240513T134000Z
DTEND;VALUE=DATE-TIME:20240513T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/132
DESCRIPTION:Title: Moment-Sum-of-Squares relaxations for variational problems\nby G
iovanni Fantuzzi (University of Erlangen) as part of Nečas Seminar on Con
tinuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and
Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nMom
ent-Sum-of-Squares (moment-SOS) relaxations are an established technique t
o compute converging sequences of lower bounds on the global minimum of fi
nite-dimensional polynomial optimization problems. In this talk\, I will d
iscuss two recent extensions of moment-SOS relaxations to infinite-dimensi
onal variational problems\, where a (possibly nonconvex) integral function
al is to be minimized over functions from a Sobolev space. The first exten
sion optimizes so-called "null Lagrangian translations" and returns certif
ied lower bounds on the global minimum of the variational problem. The sec
ond extension\, instead\, produces upper bounds by approximating minimizer
s of finite element discretizations of the variational problem. Conditions
that ensure the convergence of these upper and lower bounds to the desire
d global minimum will be discussed\, and current gaps between theory and p
ractice will be illustrated by means of examples.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hywel Normington (University of Strathclyde)
DTSTART;VALUE=DATE-TIME:20240422T134000Z
DTEND;VALUE=DATE-TIME:20240422T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/133
DESCRIPTION:Title: A decoupled\, convergent and fully linear algorithm for the Landau-L
ifshitz-Gilbert equation with magnetoelastic effects\nby Hywel Norming
ton (University of Strathclyde) as part of Nečas Seminar on Continuum Mec
hanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physics\,
Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nThe mechanica
l and magnetic properties of ferromagnetic materials are strongly coupled.
Applying a stress to a ferromagnetic material changes the magnetic state\
, and applying a magnetic field deforms it. These fall collectively under
the phenomena of "magnetostriction". We consider the coupled system of the
Landau-Lifshitz-Gilbert (LLG) equation and conservation of momentum to de
scribe magnetostrictive processes. For this nonlinear system of time-depen
dent partial differential equations\, we present a decoupled and unconditi
onally convergent integrator based on linear finite elements in space and
a one-step method in time. Compared to previous works on this problem\, fo
r our method\, we prove a discrete energy law that mimics that of the cont
inuous problem. Moreover\, we do not employ a nodal projection to impose t
he unit-length constraint on the discrete magnetization\, so that the stab
ility of the method does not require weakly acute meshes. Furthermore\, ou
r integrator and its analysis hold for a more general setting\, including
body forces and traction\, and a more general representation of the magnet
ostrain.\n\nH. Normington and M. Ruggeri\, A decoupled\, convergent and fu
lly linear algorithm for the Landau--Lifshitz--Gilbert equation with magne
toelastic effects.\n(under review)\,\nhttps://arxiv.org/abs/2309.00605v2\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:break
DTSTART;VALUE=DATE-TIME:20240129T144000Z
DTEND;VALUE=DATE-TIME:20240129T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/134
DESCRIPTION:by break as part of Nečas Seminar on Continuum Mechanics\n\nL
ecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Uni
versity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:break
DTSTART;VALUE=DATE-TIME:20240205T144000Z
DTEND;VALUE=DATE-TIME:20240205T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/135
DESCRIPTION:by break as part of Nečas Seminar on Continuum Mechanics\n\nL
ecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Uni
versity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:break
DTSTART;VALUE=DATE-TIME:20240212T144000Z
DTEND;VALUE=DATE-TIME:20240212T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/136
DESCRIPTION:by break as part of Nečas Seminar on Continuum Mechanics\n\nL
ecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Uni
versity\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Scherz (University of Wuerzburg)
DTSTART;VALUE=DATE-TIME:20240408T134000Z
DTEND;VALUE=DATE-TIME:20240408T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/137
DESCRIPTION:Title: Weak Solutions to Mathematical Models of the Interaction between Flu
ids\, Solids and Electromagnetic Fields\nby Jan Scherz (University of
Wuerzburg) as part of Nečas Seminar on Continuum Mechanics\n\nLecture hel
d in Room K3\, Faculty of Mathematics and Physics\, Charles University\,
Sokolovská 83 Prague 8..\n\nAbstract\nWe prove the existence of weak sol
utions to two systems of PDEs modeling interactions between fluids\, solid
s and electromagnetic fields. The first problem we consider describes the
motion of an insulating rigid body through an electrically conducting inco
mpressible fluid. The existence of weak solutions to this problem is achie
ved via a time discretization and an application of the Brinkman penalizat
ion. The second considered problem deals with the evolution of the deforma
tion and the magnetization of a magnetoelastic material and is solved via
an application of De Giorgi's minimizing movements scheme.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Easter Monday
DTSTART;VALUE=DATE-TIME:20240401T134000Z
DTEND;VALUE=DATE-TIME:20240401T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/138
DESCRIPTION:Title: no talk\nby Easter Monday as part of Nečas Seminar on Continuum
Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physic
s\, Charles University\, Sokolovská 83 Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eduard Rohan (University of West Bohemia\, Pilsen)
DTSTART;VALUE=DATE-TIME:20240325T144000Z
DTEND;VALUE=DATE-TIME:20240325T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/139
DESCRIPTION:Title: Homogenization based model of flows in piezoelectric porous metamate
rials driven by peristaltic deformation\nby Eduard Rohan (University o
f West Bohemia\, Pilsen) as part of Nečas Seminar on Continuum Mechanics\
n\nLecture held in Room K3\, Faculty of Mathematics and Physics\, Charles
University\, Sokolovská 83 Prague 8..\n\nAbstract\nThe seminar talk is
devoted to the multiscale modelling of an electroactive porous material in
tended for fluid transport. Its functionality is based on the peristaltic
flow which is induced by deforming pore walls. This phenomenon is of a gre
at importance in physiology and biomechanics\, however\, as a driving mech
anism of fluid transport\, it presents and important and challenging issue
in the design of smart ``bio-inspired'' materials. We consider locally p
eriodic porous structures saturated by a Newtonian fluid. The peristaltic
deformation wave of the microchannels is induced by a convenient local con
trol of piezoelectric segments. Several issues related to the construction
of a computationally efficient two-scale metamaterial model within the ho
mogenization framework will be presented. We consider relatively small def
ormation which enables to use the linear kinematic framework. The poro-pie
zoelectric model derived in [1] is extended for the viscous fluid flow whi
le respecting the inertia effects in both the phases. Using the homogeniza
tion based on the classic asymptotic analysis\, cell problems (at the micr
olevel) are obtained which provide characteristic responses of the microst
ructures with respect to macroscopic strains\, fluid pressure and electric
potentials. These responses are needed to compute the effective (homogeni
zed) parameters of the macroscopic problem which depend on the microconfig
uration. The numerical studies demonstrate that such a linear model cannot
capture the desired pumping effect of the homogenized continuum. To achie
ve this functionality of the model\, it is necessary to account for the no
nlinearity associated with deformation-dependent microconfigurations. To a
void hurdles associated with a fully nonlinear two-scale model\, we apply
a linearization procedure based on the sensitivity analysis of the local c
haracteristic responses with respect to the deformation induced by the mac
roscopic quantities. In this way\, by virtue of the methodology introduced
in [2]\, we get first-order expansions of all the homogenized coefficient
s. The dynamic effects lead to the macroscopic flow model in a convolution
form. For this option\, a special treatment of the deformation-dependent
dynamic permeability is needed. Numerical examples illustrate efficiency o
f the proposed computational approach [3].\n\n\n[1] E. Rohan\, V. Lukeš.
On modelling nonlinear phenomena in deforming heterogeneous media using ho
mogenization and sensitivity analysis concepts. Applied Mathematics and Co
mputation (2015) 267:583-595.\n\n[2] E. Rohan\, V. Lukeš. Homogenization
of the fluid-saturated piezoelectric porous media. Int. Jour. Solids and S
tructures (2018) 147:110-125.\n\n[3] E. Rohan\, V. Lukeš. Homogenization
of peristaltic flows in piezoelectric porous media. (2023) arXiv:2304.0539
3v1\, https://doi.org/10.48550/arXiv.2304.05393\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chiara Gavioli (Czech Technical University\, Prague)
DTSTART;VALUE=DATE-TIME:20240429T134000Z
DTEND;VALUE=DATE-TIME:20240429T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/140
DESCRIPTION:Title: A model for lime consolidation of porous solids\nby Chiara Gavio
li (Czech Technical University\, Prague) as part of Nečas Seminar on Cont
inuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and P
hysics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe p
resent the first mathematical 3D model describing the process of filling t
he pores of a building material with a water-lime-mixture\, with the goal
to improve the consistency of the porous solid. Chemical reactions produce
calcium carbonate which glues the solid particles together at some distan
ce from the boundary and strengthens the whole structure. The model consis
ts of a reaction-diffusion system with a nonlinear non-smooth boundary con
dition\, coupled with the mass balance equations for the chemical reaction
. The main result consists in proving that the system has a solution for e
ach initial data from a physically relevant class. A 1D numerical test sho
ws a qualitative agreement with experimental observations.\nThis is a join
t work with B. Detmann (Universität Duisburg-Essen)\, P. Krejčí\, J. La
mač\, and Y. Namlyeyeva (Czech Technical University Prague).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Johannes Zimmer (Technical University of Munich)
DTSTART;VALUE=DATE-TIME:20240506T134000Z
DTEND;VALUE=DATE-TIME:20240506T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/141
DESCRIPTION:Title: Deriving a GENERIC system from a Hamiltonian system\nby Johannes
Zimmer (Technical University of Munich) as part of Nečas Seminar on Con
tinuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and
Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe
reconsider the problem of coarse-graining infinite-dimensional Hamiltonian
dynamics to obtain a macroscopic system that includes dissipative mechani
sms. In particular\, we study the thermodynamical implications concerning
Hamiltonians\, energy\, and entropy and the induced geometric structures.
The Hamiltonian model is described by a unitary group\, and is time-revers
ible. The coarse-grained description includes dissipative effects\, is des
cribed by a contraction semigroup\, and is thus irreversible. The concepts
of dilations and contractions will be described as they provide a link be
tween dissipative semigroups and unitary groups. The coarse-grained versio
n will be shown to have GENERIC (General Equations for Non-Equilibrium Rev
ersible Irreversibe Coupling) structure\, with conserved energy\, nondecre
asing entropy and an Onsager operator describing the dissipation.\n\n This
is joint work with Alex Mielke and Mark Peletier.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giuseppe Tomassetti (University of Roma Tre)
DTSTART;VALUE=DATE-TIME:20240318T144000Z
DTEND;VALUE=DATE-TIME:20240318T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/142
DESCRIPTION:Title: A mechanical model of ocular bulb vibrations and implications for ac
oustic tonometry\nby Giuseppe Tomassetti (University of Roma Tre) as p
art of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\,
Faculty of Mathematics and Physics\, Charles University\, Sokolovská 83
Prague 8..\n\nAbstract\nWe propose a comprehensive mechanical model of oc
ular bulb vibrations and discuss its implications for acoustic tonometry.
The model describes the eye wall as a spherical\, pre-stressed elastic she
ll containing a viscoelastic material and accounts for the interaction bet
ween the elastic corneoscleral shell and the viscoelastic vitreous humor.
We investigate the natural frequencies of the system and the corresponding
vibration modes\, expanding the solution in terms of scalar and vector sp
herical harmonics. From a quantitative point of view\, our findings reveal
that the eyebulb vibration frequencies significantly depend on IOP. This
dependency has two origins: "geometric" stiffening\, due to an increase of
the pre-stress\, and "material" stiffening\, due to the nonlinearity of t
he stress-strain curve of the sclera. The model shows that the second effe
ct is by far dominant. We also find that the oscillation frequencies depen
d on ocular rigidity\, but this dependency is important only at relatively
large values of IOP. Thus close to physiological conditions\, IOP is the
main determinant of ocular vibration frequencies. The vitreous rheological
properties are found to mostly influence vibration damping. This study co
ntributes to the understanding of the mechanical behavior of the eye under
dynamic conditions and thus has implications for non-contact intraocular
pressure measurement techniques\, such as acoustic tonometry. The model ca
n also be relevant for other ocular pathological conditions\, such as trau
matic retinal detachment\, which are believed to be influenced by the dyna
mic behavior of the eye.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Václav Mácha (Institute of Mathematics\, Czech Academy of Scienc
es)
DTSTART;VALUE=DATE-TIME:20240304T144000Z
DTEND;VALUE=DATE-TIME:20240304T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/143
DESCRIPTION:Title: ANALYSIS OF A SYSTEM MODELLING THE INTERACTION BETWEEN THE MOTION OF
PISTON-SPRING AND A VISCOUS GAS\nby Václav Mácha (Institute of Math
ematics\, Czech Academy of Sciences) as part of Nečas Seminar on Continuu
m Mechanics\n\nLecture held in Room K3\, Faculty of Mathematics and Physi
cs\, Charles University\, Sokolovská 83 Prague 8..\n\nAbstract\nWe are c
oncerned with a one-dimensional flow of a compressible\nfluid which may be
seen\nas a simplification of the flow of fluid in a long\, thin pipe. We
assume\nthe pipe is on one side\,\nending by a spring. The other side of t
he pipe is left open – there\, we\nassume either inflow or outflow\nboun
dary conditions. Such a situation can be understood as a toy model for\nhu
man lungs. We tackle\nthe question of uniqueness and the existence of a st
rong solution for a\nsystem modeling the above process\,\nspecial emphasis
is laid upon the estimate of the maximal time of\nexistence.\nThis is a j
oint work with Sabrine Chebbi and Šárka Nečasová\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Krejčí (Czech Technical University in Prague\, Faculty of
Civil Engineering)
DTSTART;VALUE=DATE-TIME:20240520T134000Z
DTEND;VALUE=DATE-TIME:20240520T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/144
DESCRIPTION:Title: Hysteresis in porous media\nby Pavel Krejčí (Czech Technical U
niversity in Prague\, Faculty of Civil Engineering) as part of Nečas Semi
nar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathem
atics and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbs
tract\nWe propose a model for fluid diffusion in partially saturated porou
s media taking\ninto account saturation-dependent permeability as well as
hysteresis effects in the pressure saturation relation. The resulting math
ematical problem leads to a diffusion equation for\nthe pressure in an N-d
imensional domain with a Preisach hysteresis operator under the time\nderi
vative and in the diffusion coefficient. The problem is doubly degenerate
in the sense\nthat the saturation range is bounded\, and no a priori contr
ol of the time derivative of the\npressure is available. We discuss the co
nditions for existence and uniqueness of a solution\nto the problem with o
r without gravity effects in appropriate function spaces\, as well as the\
nquestion of bounded speed of propagation. This is a joint work with Chiar
a Gavioli.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:summer break
DTSTART;VALUE=DATE-TIME:20240527T134000Z
DTEND;VALUE=DATE-TIME:20240527T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/145
DESCRIPTION:Title: We'll continue on September 30\, 2024\nby summer break as part
of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Fac
ulty of Mathematics and Physics\, Charles University\, Sokolovská 83 Pra
gue 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matteo Negri (University of Pavia)
DTSTART;VALUE=DATE-TIME:20241021T134000Z
DTEND;VALUE=DATE-TIME:20241021T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/146
DESCRIPTION:Title: Rate-independent evolutions in phase-field fracture generated by equ
ilibrium configurations\nby Matteo Negri (University of Pavia) as part
of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\, Fa
culty of Mathematics and Physics\, Charles University\, Sokolovská 83 Pr
ague 8..\n\nAbstract\nIn the phase-field approach\, and in other regulariz
ed fracture models\, rate-independent (quasi-static) evolutions are usuall
y obtained by means of time-discrete schemes\, providing at each time an e
quilibrium configuration of the system. Numerically\, equilibria are comp
uted by descent methods for the free energy (e.g. staggered\, monolithic e
tc.) endowed with a suitable irreversibility constraint on phase-field par
ameter (e.g. monotonicity in time). The time-continuous limit evolution i
s characterized in terms of evolutionary variational inequalities and in t
erms of Griffith's criterion. The study of the limit evolution reveals a c
ouple of propagation regimes: stable (or steady state) and unstable (or ca
tastrophic). In the stable regime the evolution is simultaneous (in displa
cement and phase field parameter) and satisfies Griffith's criterion in te
rms of toughness and phase field energy release rate. In the unstable regi
me the evolution is not necessarily simultaneous and may not satisfy Griff
ith's criterion. Energy identity holds in general with an instantaneous dr
op of energy in unstable times. The monotonicity constraint turns out to b
e fully thermodynamically consistent along the whole evolution. Technicall
y\, the proof relies on: (a) the strong convergence of the phase field par
ameter\, (b) Kuratowski convergence of parametrized discrete times\, (c) t
he limit of the power identity. The result is very general since it works
independently of the scheme employed in the incremental problem\, it holds
for instance for AT1 and AT2 energies\, in plane strain and plane stress
settings. Numerically\, we compare energies\, energy release rates and evo
lutions computed in the sharp crack and in the phase field setting for a c
ouple of reference benchmarks: the double cantilever beam (for steady stat
e propagation) and the single edge notch under tension (for unstable propa
gation).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vladislav Mantič (University of Sevilla)
DTSTART;VALUE=DATE-TIME:20240930T134000Z
DTEND;VALUE=DATE-TIME:20240930T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/147
DESCRIPTION:Title: Stress singularities in BVPs with Robin and Ventcel boundary conditi
ons. Applications in FEM modeling\nby Vladislav Mantič (University of
Sevilla) as part of Nečas Seminar on Continuum Mechanics\n\nLecture held
in Room K3\, Faculty of Mathematics and Physics\, Charles University\, S
okolovská 83 Prague 8..\n\nAbstract\nLinear-elastic antiplane-strain pro
blems governed by the 2D Laplace equation are considered in domains with c
orners and cracks. First\, power-logarithmic stress singularities in Neuma
nn-Robin BVPs in infinite corner (polar sector) type domains are studied.
Asymptotic solutions given by a double asymptotic series with the main and
the associated shadow terms are presented. An application of such an asym
ptotic series to the numerical solution of the BVP of a crack in a thin ad
hesive interface layer modeled by the spring interface is shown by impleme
nting a finite element method (FEM) procedure. Second\, similar asymptotic
analysis of power-logarithmic stress singularities in Dirichlet-Robin BVP
s in infinite corners with a power-law variation (with the distance to the
corner apex) of the governing coefficient in the Robin boundary condition
is presented. An application of such an asymptotic solution to the BVPs o
f bridged cracks with a power-law variation of the stiffness of linear-ela
stic spring distribution is presented. Finally\, a power-logarithmic stres
s singularity in a Dirichlet-Ventcel BVP in half domain is studied by a si
milar asymptotic procedure. An application of this asymptotic solution to
the FEM solution of a BVP with a finite and open Gurtin-Murdoch material s
urface is presented.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pablo Pedregal (University of Castilla-La Mancha)
DTSTART;VALUE=DATE-TIME:20241118T144000Z
DTEND;VALUE=DATE-TIME:20241118T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/148
DESCRIPTION:Title: Discoveries and surprises in the non-local Calculus of Variations\nby Pablo Pedregal (University of Castilla-La Mancha) as part of Nečas
Seminar on Continuum Mechanics\n\nInteractive livestream: https://cesnet.z
oom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Zz09\nView-only lives
tream: https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ\nLecture h
eld in Room K3\, Faculty of Mathematics and Physics\, Charles University\
, Sokolovská 83 Prague 8..\n\nAbstract\nPeridynamics stands as a main ap
plication of non-local variational problems in Continuum Mechanics. Yet fr
om the mathematical point of view many of the important issues behind are
formally similar\, after suitable non-local reinterpretation of tools\, to
the classic local framework. Though this is no doubt surprising and reass
uring\, we will try to push non-locality to find some situations where thi
ngs are really different. Some of the simplest examples will serve to illu
strate how different things may be.\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cristiana De Filippis (University of Parma\, Italy)
DTSTART;VALUE=DATE-TIME:20241125T144000Z
DTEND;VALUE=DATE-TIME:20241125T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/149
DESCRIPTION:Title: Regularity problems in the Calculus of Variations\nby Cristiana
De Filippis (University of Parma\, Italy) as part of Nečas Seminar on Con
tinuum Mechanics\n\nInteractive livestream: https://cesnet.zoom.us/j/94319
936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Zz09\nView-only livestream: https:/
/www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ\nLecture held in Room K3
\, Faculty of Mathematics and Physics\, Charles University\, Sokolovská
83 Prague 8..\n\nAbstract\nRegularity theory and the Calculus of Variatio
ns are unavoidably linked to each other\,\n as in fact\, regularity techni
ques essentially serve to show weak or distributional solutions are in\n f
act classical solutions. Therefore\, regularity ensures solvability. This
is a topic that has been tremendously developed over the last 100 years\,
and I will try to give an overview starting from very\n classical results\
, passing through the fundamental contributions of De Giorig and Nash\, e
ventually\n approaching some of the most recent developments involving non
uniformly elliptic problems.\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
BEGIN:VEVENT
SUMMARY:////////////////
DTSTART;VALUE=DATE-TIME:20241028T144000Z
DTEND;VALUE=DATE-TIME:20241028T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/150
DESCRIPTION:Title: National Holiday - no seminar lecture\nby //////////////// as pa
rt of Nečas Seminar on Continuum Mechanics\n\nLecture held in Room K3\,
Faculty of Mathematics and Physics\, Charles University\, Sokolovská 83
Prague 8..\nAbstract: TBA\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:X-mas
DTSTART;VALUE=DATE-TIME:20241223T144000Z
DTEND;VALUE=DATE-TIME:20241223T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/151
DESCRIPTION:by X-mas as part of Nečas Seminar on Continuum Mechanics\n\nI
nteractive livestream: https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWE
hhQ1U4TzZGc2FDQVM4Zz09\nView-only livestream: https://www.youtube.com/chan
nel/UCn9vmevniyXXLEr7VBp5cCQ\nLecture held in Room K3\, Faculty of Mathem
atics and Physics\, Charles University\, Sokolovská 83 Prague 8..\nAbstr
act: TBA\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anna Hundertmark (Rheinland-Pfälzische Technische Universität)
DTSTART;VALUE=DATE-TIME:20241007T134000Z
DTEND;VALUE=DATE-TIME:20241007T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/152
DESCRIPTION:Title: Modeling of carotid artery hemodynamics towards a CFD database for s
troke risk assessment\nby Anna Hundertmark (Rheinland-Pfälzische Tec
hnische Universität) as part of Nečas Seminar on Continuum Mechanics\n\n
Lecture held in Room K3\, Faculty of Mathematics and Physics\, Charles Un
iversity\, Sokolovská 83 Prague 8..\n\nAbstract\nIn medicine\, the risk
assessment of strokes caused by pathological\nirregularities in the bifurc
ation of the carotid artery plays a major\nrole in the patient's optimal t
reatment decision.\nThis decision-making process can be greatly enhanced b
y detailed flow\nfield data obtained from simulations using patient-specif
ic arterial\nmorphologies. We present our numerical modeling approach to c
reate a CFD\ndatabase that can guide stroke risk assessment\, including he
modynamic shear risk\nmetrics. We investigate the multi-directional behavi
or of wall shear\nstress (WSS) based on specially\nconstructed longitudina
l tangent vectors using a center-line projection\napproach and present the
utility of longitudinal WSS evaluation for\ndetecting opposing or transve
rse WSS in slow patient-specific flow. In\nour fluid-structure interactio
n model\,\nwe generalize the assumption of linear elasticity by a strain-d
ependent\nelastic modulus that is consistent with laboratory measurements
of\ncompliance and distensibility. Finally\, we present the established\nw
orking pipeline to generate CFD\ndata for a large number of patient-specif
ic geometries. Created\nhemodynamic datasets can be used for visual atlase
s and comparative\nanalysis or explored by neural networks.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matteo Caggio (Institute of mathematics\, Czech Academy of Science
s)
DTSTART;VALUE=DATE-TIME:20241014T134000Z
DTEND;VALUE=DATE-TIME:20241014T151000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/153
DESCRIPTION:Title: Vanishing viscosity limit for the compressible Navier-Stokes equatio
ns with non-linear density dependent viscosities\nby Matteo Caggio (In
stitute of mathematics\, Czech Academy of Sciences) as part of Nečas Semi
nar on Continuum Mechanics\n\nLecture held in Room K3\, Faculty of Mathem
atics and Physics\, Charles University\, Sokolovská 83 Prague 8..\n\nAbs
tract\nIn a three-dimensional bounded domain\, we consider the compressibl
e\nNavier-Stokes equations for a barotropic fluid with general non-linear\
ndensity dependent viscosities and no- slip boundary conditions. A\nnonlin
ear drag term is added to the momentum equation. We establish two\nconditi
onal Kato-type criteria for the convergence of the weak solutions\nto such
a system towards the strong solution of the compressible Euler\nsystem wh
en the viscosity coefficient and the drag term parameter tend\nto zero.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Angela Bašič-Šiško (University of Rijeka)
DTSTART;VALUE=DATE-TIME:20241104T144000Z
DTEND;VALUE=DATE-TIME:20241104T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/154
DESCRIPTION:Title: Real micropolar gas flow model\nby Angela Bašič-Šiško (Unive
rsity of Rijeka) as part of Nečas Seminar on Continuum Mechanics\n\nLectu
re held in Room K3\, Faculty of Mathematics and Physics\, Charles Univers
ity\, Sokolovská 83 Prague 8..\n\nAbstract\nThe micropolar real gas mode
l\, which extends the traditional fluid\n dynamics model to account for mi
cro-effects\, is explored. This model\n introduces additional rotational d
egrees of freedom to capture the\n behavior of the internal fluid structur
e. By incorporating the\n equation\n of state for real gases\, a shift fro
m the ideal gas model to a more\n general case is achieved. The mathematic
al framework of this model is\n discussed\, and results on the existence\,
uniqueness\, and large-time\n behavior of the solution for one-dimensiona
l and spherically symmetric\n flows are presented.\n Furthermore\, we cons
ider combustion within the fluid to form the\n reactive micropolar real ga
s model. This model additionally\n incorporates\n the chemical reactivity
of the gas mixture\, enabling the simulation of\n reactive flows such as f
uel combustion\, detonation in aerospace\n engineering\, and the modeling
of gaseous stars. Results on the\n well-posedness of this model are also p
resented.\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:x-mas
DTSTART;VALUE=DATE-TIME:20241216T144000Z
DTEND;VALUE=DATE-TIME:20241216T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/155
DESCRIPTION:by x-mas as part of Nečas Seminar on Continuum Mechanics\n\nI
nteractive livestream: https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWE
hhQ1U4TzZGc2FDQVM4Zz09\nView-only livestream: https://www.youtube.com/chan
nel/UCn9vmevniyXXLEr7VBp5cCQ\nLecture held in Room K3\, Faculty of Mathem
atics and Physics\, Charles University\, Sokolovská 83 Prague 8..\nAbstr
act: TBA\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
BEGIN:VEVENT
SUMMARY:x-mas
DTSTART;VALUE=DATE-TIME:20241230T144000Z
DTEND;VALUE=DATE-TIME:20241230T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/156
DESCRIPTION:by x-mas as part of Nečas Seminar on Continuum Mechanics\n\nI
nteractive livestream: https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWE
hhQ1U4TzZGc2FDQVM4Zz09\nView-only livestream: https://www.youtube.com/chan
nel/UCn9vmevniyXXLEr7VBp5cCQ\nLecture held in Room K3\, Faculty of Mathem
atics and Physics\, Charles University\, Sokolovská 83 Prague 8..\nAbstr
act: TBA\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
BEGIN:VEVENT
SUMMARY:TL
DTSTART;VALUE=DATE-TIME:20241111T144000Z
DTEND;VALUE=DATE-TIME:20241111T161000Z
DTSTAMP;VALUE=DATE-TIME:20241107T162715Z
UID:NSCM/157
DESCRIPTION:by TL as part of Nečas Seminar on Continuum Mechanics\n\nInte
ractive livestream: https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ
1U4TzZGc2FDQVM4Zz09\nView-only livestream: https://www.youtube.com/channel
/UCn9vmevniyXXLEr7VBp5cCQ\nLecture held in Room K3\, Faculty of Mathemati
cs and Physics\, Charles University\, Sokolovská 83 Prague 8..\nAbstract
: TBA\n
LOCATION:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
URL:https://cesnet.zoom.us/j/94319936814?pwd=Y0pRL0FpWEhhQ1U4TzZGc2FDQVM4Z
z09
URL:https://www.youtube.com/channel/UCn9vmevniyXXLEr7VBp5cCQ
END:VEVENT
END:VCALENDAR