We study the propagation properties of the solutions of the finite-difference space semi-discrete wave equation on an uniform grid of the whole Euclidean space. We provide a construction of high frequency wave packets that propagate along the corresponding bi-characteristic rays of Geometric Optics with a group velocity arbitrarily close to zero. Our analysis is motivated by control theoretical issues. In particular, the continuous wave equation has the so-called observability property: for a sufficiently large time, the total energy of its solutions can be estimated in terms of the energy concentrated in the exterior of a compact set. This fails to be true, uniformly on the mesh-size parameter, for the semi-discrete schemes and the observability constant blows-up at an arbitrarily large polynomial order. Our contribution consists in providing a rigorous derivation of those wave packets and in analyzing their behavior near that ray, by taking into account the subtle added dispersive effects that the numerical scheme introduces.
Semi-discretization for stochastic scalar conservation laws with multiple rough fluxes
Max-Planck Institute for Mathematics in the Sciences（马克斯·普朗克科学促进学院数学研究所）；Sorbonne Universités, UPMC Univ. Paris 06, CNRS, INRIA, UMR 7598, Laboratoire Jacques-Louis Lions（索邦大学，巴黎第六大学，法国国家科学研究中心，法国国家信息与自动化研究所，雅克-路易·利翁斯实验室）；Department of Mathematics University of Chicago（芝加哥大学数学系）
Nonlinear damped partial differential equations and their uniform discretizations
Université de Lorraine（洛林大学）；CNRS（法国国家科学研究中心）；Sorbonne Universités, UPMC Univ Paris 06（索邦大学，巴黎第六大学）；Laboratoire Jacques-Louis Lions（雅克-路易·利翁斯实验室）；Institut Universitaire de France（法兰西学院）
A Mathematical Description of the IDSA for Supernova Neutrino transport, its discretization and a comparison with a finite volume scheme for Boltzmann's Equation
