Journées de Mathématiques Appliquées <br/> Conférence en l'honneur de Laurence Halpern

Session

Session Poster

21 janv. 2015, 18:00

Amphithéâtre Hermite (Institut Henri Poincaré)

32. A new approach for preconditioning discontinuous Galerkin discretizations

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...

28. Analyse d'erreur a posteriori et raffinement auto-adaptatif pour les éléments finis de frontière en acoustique

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.

30. Comparison of Neuman-Neuman and Optimal Schwarz Methods with Many Subdomains in one Spatial Dimensions

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...

24. D-solutions for doubly reflected BSDEs

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.

33. Factorizations, Sweeping, Source Transfer, Potentials and Schwarz: One Algorithm

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...

29. Méthodes asynchrones de haute précision pour la modélisation de phénomènes multi-échelles

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...

31. Space-time domain decomposition methods for mixed formulations of flow and transport problems in porous media

21/01/2015 18:00

présentation murale

Flow and transport problems in porous media are well-known for their high computational cost. In the simulation of an underground nuclear waste disposal site, one has to work with extremely different length and time scales, and highly variable coefficients while satisfying strict accuracy requirements. One strategy for tackling these difficulties is to apply a non-overlapping domain...

25. The variational spline method for solving Troesch's problem

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...

34. Wave-Ray Multigrid Method for The 1D Helmholtz Equation A precise mathematical formulation and first analysis

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.