Jeffrey Rauch
(University of Michigan)
20/01/2015 09:15
Reports on the construction of absorbing layers for the
one dimensional linearized water wave equation. The equation
is nonlocal forcing it immediately out of the realm of standard
ideas. A key and simple is idea is one way water wave equations
related to D'Alembert's method. Joint work with Izbicki, Karni, Carney,
Abgrall, and Prigge (in chronological order).
Jean-Claude Nedelec
(CMAP Polytechnique)
20/01/2015 10:30
We introduce four integral operators closely related to the Laplace equation in three-dimensions on the circular unit disc. Two of them are closed to the simple layer on the disc and the other two are related to the hyper singular operator. Contrary to the case of a closed domain, these operators no longer map fractional Sobolev spaces in a dual fashion but degenerate into different subspaces...
Nick TERFETHEN
(University of Oxford)
20/01/2015 11:15
Everybody has heard of the Faraday cage effect, in which
a wire mesh does a good job of blocking electric fields.
Surely the mathematics of such a famous and useful phenomenon
has been long ago worked out and written up in the textbooks?
It seems to be not so. One reason may be that that the
effect is not as simple as one might expect: it depends on
the wires having finite radius. ...
Jean-Claude Guillot
20/01/2015 14:30
We consider Hamiltonians with cutoffs which are self-adjoint operators in appropriate Fock spaces with a unique ground state. A limiting Absorbtion Principle is proved
Yann Brenier
(CMLS École Polytechnique)
20/01/2015 16:30
In the 1990, Moffatt discussed a dissipative model of
Magneto-hydrodynamics (that he called “magnetic relaxation” but could
also be called “Darcy” or “Stokes” MHD), in order to get stationary
solutions of the Euler equations with prescribed topology. We will
discuss the corresponding PDEs and some concepts of generalized
solutions related both to P.-L. Lions’ dissipative solutions to...
Abderrahmane BENDALI
(INSA Toulouse)
21/01/2015 11:15
Usual Foldy's model is used to approximate a multiple
scattering problem involving small scatterers by monopole
scatterers. Using the method of matched asymptotic expansions, with
P. H. Cocquet and S. Tordeux, we have first proved that the scattered
field can be approximated at any order of accuracy by multipoles.
This first provides a mathematical justification for the Foldy model
and...
Jean-Jacques Marigo
(LMS École Polytechnique)
21/01/2015 15:15
It is well-accepted that Griffith-like models are appropriate for crack propagation at the scale of a structure, but inadequate for the modeling of crack nucleation in brittle materials. Arguably, finer models, where a microscopic (material) length scale plays a fundamental role, are necessary to determine the critical load and crack geometry at the onset. The consistent combined modeling and...
Oana Ciobanu
(Paris 13 et Onera)
21/01/2015 16:30
A space-time domain decomposition algorithm for the
compressible Navier–Stokes problem has been designed, with the aim of implementing it in three dimensions, in an industrial code. We improve the SWR method adding an adaptive time stepping inside each time window and compare its performances for different second order explicit/implicit algorithms, on complexe cases.
Georges-Henri Cottet
21/01/2015 17:15
In this talk we show how numerical models and algorithms can be
tailored to HPC platforms to address multiscale problems occurring in
turbulent transport.
Soheil HAJIAN
(Université de Genève)
21/01/2015 18:00
présentation murale
Domain decomposition preconditioners and in particular the additive
Schwarz method are favorite preconditioners for classical finite
element methods (FEM). There is a huge effort in designing similar
preconditioners for discontinuous Galerkin (DG) discretizations. It
has been shown that additive Schwarz methods use different mechanisms
for convergence when applied to a DG discretization...
Marc Bakri
(ONERA)
21/01/2015 18:00
présentation murale
Nous présenterons plusieurs indicateurs d'erreur /a posteriori /adaptés aux méthodes d'éléments finis utilisées pour discrétiser les équations intégrales en acoustique 2D.
En particulier, nous introduirons une nouvelle classe d'estimateurs fiables et efficaces
dont la construction est basée sur une nouvelle technique de localisation des normes de Sobolev fractionnaires.
Faycal Chaouqui
(Université de Genève)
21/01/2015 18:00
présentation murale
Optimal Schwarz methods and Neuman-Neuman methods have
for two subdomains both the interesting property that they can lead to
nil-potent iteration matrices. We study in this poster if this property
can also be obtained for the case of a strip decomposition into many
subdomains. We show that only the optimal Schwarz method can
lead in this case to a nil-potent iteration matrix, and that...
Mme
imen hassairi
(Did not come to the conference)
21/01/2015 18:00
présentation murale
We are concerned with the problem of existence and uniqueness of a solution in class D for the backward stochastic differential equations (BSDEs for short) with two continuous reflecting barriers which are completely separated. We consider that the data are Lp-integrable with p = 1.
Hui Zhang
(Université de Genève)
21/01/2015 18:00
présentation murale
Many of the modern iterative algorithms for the Helmholtz (or a more general PDE) operator
have common ingredients. We show that all these algorithms can be understood in the
framework of optimized Schwarz methods. They only differ in the particular choice on how
to approximate the optimal transmission condition which contains a Dirichlet to Neumann operator,
in the choice of the subdomain...
Asma Toumi
(ONERA)
21/01/2015 18:00
présentation murale
La simulation numérique est de systèmes physiques multi-échelles est souvent synonyme de calculs coûteux et particulièrement longs.
En effet, dans les méthodes classiques d’intégration temporelle, le pas de temps local le plus faible est souvent limitant pour le pas de temps global d'intégration.
Notre étude porte sur un schéma asynchrone permettant de lever cette limitation.
Ce formalisme...
M.
Zakaria Belhaj
(Did not come to the conference)
21/01/2015 18:00
présentation murale
Troesch's problem arises in the investigation of the confinement of a plasma column by radiation pressure. Recently, this problem has been studied extensively.
We present a variational approximation method for solving Troesch's problem. The existence and the uniqueness of this problem are shown. Moreover, we construct a sequence of solutions of the problem from the number of knots in the...
Shu-Lin Wu
(Université de Genève)
21/01/2015 18:00
présentation murale
We try to analyze the convergence properties of the wave-ray multigrid method for the Helmholtz equation in
the 1D case. We present the details of the method and perform a local Fourier analysis for the convergence behavior.
This preliminary study shows no remarkable evidence of advantages by using the wave-ray idea.
Pierre Degond
(Imperial College London)
22/01/2015 09:15
Collective dynamics refers to the ability of motile agents to achieve
large-scale coordination through purely local interactions. Systems
exhibiting collective dynamics can be found in the living world (motor
proteins, cells, birds, pedestrians) as well as in the social world
(opinion, wealth). Collective dynamics challenges the existing theories
relating microscopic to macroscopic...
Mohamed Amara
(Université de Pau)
22/01/2015 10:30
the presentation deals about a procedure for selecting basis function
orientation to improve the e?fficiency of solution methodologies that
employ local plane-wave approximations. The proposed adaptive
approach consists of a local wave tracking strategy. Each plane-wave
basis set within considered elements of the mesh partition is
individually or collectively rotated to best align one...
