Existence and stability of non-equilibrium steady states of a weakly non-linear kinetic Fokker-Planck equation in a domain

TL;DR

This paper proves the existence and stability of non-equilibrium steady states for a weakly non-linear kinetic Fokker-Planck equation in bounded domains with Maxwell boundary conditions, extending previous results from torus to bounded domains.

Contribution

It generalizes prior work on non-linear kinetic Fokker-Planck equations to bounded domains with space-dependent boundary conditions, establishing existence and stability of steady states.

Findings

Existence of non-equilibrium steady states in bounded domains.

Stability of these steady states in the weakly non-linear regime.

Extension of previous torus results to bounded spatial domains.

Abstract

We study a weakly non-linear Fokker-Planck equation with BGK heat thermostats in a spatially bounded domain with conservative Maxwell boundary conditions, presenting a space-dependent accommodation coefficient and a space-dependent temperature on the spatial boundary. The model is based from a problem introduced in [E. A. Carlen, R. Esposito, J. L. Lebowitz, R. Marra, and C. Mouhot. Approach to the steady state in kinetic models with thermal reservoirs at different temperatures. J. Stat. Phys., 172(2):522--543, 2018] where the authors studied the properties of the non-equilibrium steady states for non-linear kinetic Fokker-Planck equations with BGK thermostats in the torus. We generalize those results for bounded domains using the recent results presented in [K. Carrapatoso, P. Gabriel, R. Medina, and S. Mischler. Constructive krein-rutman result for kinetic Fokker-Planck equations in a domain, 2024] for the study of general kinetic Fokker-Planck equations with Maxwell boundary conditions. More precisely, in a weakly non-linear regime, we obtain the existence of a non-equilibrium steady state and its stability in the perturbative regime. .