31 research outputs found
Estimates for the large time behavior of the Landau equation in the Coulomb case
This work deals with the large time behaviour of the spatially homogeneous
Landau equation with Coulomb potential. Firstly, we obtain a bound from below
of the entropy dissipation by a weighted relative Fisher information of
with respect to the associated Maxwellian distribution, which leads to a
variant of Cercignani's conjecture thanks to a logarithmic Sobolev inequality.
Secondly, we prove the propagation of polynomial and stretched exponential
moments with an at most linearly growing in time rate. As an application of
these estimates, we show the convergence of any (- or weak) solution to the
Landau equation with Coulomb potential to the associated Maxwellian equilibrium
with an explicitly computable rate, assuming initial data with finite mass,
energy, entropy and some higher -moment. More precisely, if the initial
data have some (large enough) polynomial -moment, then we obtain an
algebraic decay. If the initial data have a stretched exponential -moment,
then we recover a stretched exponential decay
Periodic long-time behaviour for an approximate model of nematic polymers
We study the long-time behaviour of a nonlinear Fokker-Planck equation, which
models the evolution of rigid polymers in a given flow, after a closure
approximation. The aim of this work is twofold: first, we propose a microscopic
derivation of the classical Doi closure, at the level of the kinetic equation ;
second, we prove the convergence of the solution to the Fokker-Planck equation
to periodic solutions in the long-time limit
Mathematical analysis of a one-dimensional model for an aging fluid
We study mathematically a system of partial differential equations arising in
the modelling of an aging fluid, a particular class of non Newtonian fluids. We
prove well-posedness of the equations in appropriate functional spaces and
investigate the longtime behaviour of the solutions
The Navier-Stokes-Vlasov-Fokker-Planck system near equilibrium
This paper is concerned with a system that couples the incompressible Navier-Stokes equations to the Vlasov-Fokker-Planck equation. Such a system arises in the modeling of sprays, where a dense phase interacts with a disperse phase. The coupling arises from the Stokes drag force exerted by a phase on the other. We study the global-in-time existence of classical solutions for data close to an equilibrium. We investigate further regularity properties of the solutions as well as their long time behavior. The proofs use energy estimates and the hypoelliptic structure of the system
Self correction of refractive error among young people in rural China: results of cross sectional investigation
Objective To compare outcomes between adjustable spectacles and conventional methods for refraction in young people
The incompressible limit in type critical spaces
International audienceThis paper aims at justifying the low Mach number convergence to the incompressible Navier-Stokes equations for viscous compressible flows in the ill-prepared data case. The fluid domain is either the whole space, or the torus. A number of works have been dedicated to this classical issue, all of them being, to our knowledge, related to spaces and to energy type arguments. In the present paper, we investigate the low Mach number convergence in the type critical regularity framework. More precisely, in the barotropic case, the divergence-free part of the initial velocity field just has to be bounded in the critical Besov space for some suitable We still require type bounds on the low frequencies of the potential part of the velocity and on the density, though, an assumption which seems to be unavoidable in the ill-prepared data framework, because of acoustic waves. In the last part of the paper, our results are extended to the full Navier-Stokes system for heat conducting fluids
THE OBERBECK-BOUSSINESQ APPROXIMATION IN CRITICAL SPACES
Abstract. In this paper we study the validity of the so-called Oberbeck-Boussinesq approximation for compressible viscous perfect gases in the whole three-dimensional space. Both the cases of fluids with positive heat conductivity and zero conductivity are considered. For small perturbations of a constant equilibrium, we establish the global existence of unique strong solutions in a critical regularity functional framework. Next, taking advantage of Strichartz estimates for the associated system of acoustic waves, and of uniform estimates with respect to the Mach number, we obtain all-time convergence to the Boussinesq system with a explicit decay rate. hal-00795419, version 1- 16 Apr 2013 1