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Boltzmann equation with mixed boundary condition

Hongxu Chen, Renjun Duan

Abstract

We study the Boltzmann equation in a smooth bounded domain featuring a mixed boundary condition. Specifically, gas particles experience specular reflection in two parallel plates, while diffusive reflection occurs in the remaining portion between these two specular regions. The boundary is assumed to be motionless and isothermal. Our main focus is on constructing global-in-time small-amplitude solutions around global Maxwellians for the corresponding initial-boundary value problem. The proof relies on the $L^2$ hypocoercivity at the linear level, utilizing the weak formulation and various functional inequalities on the test functions, such as Poincaré and Korn inequalities. It also extends to the linear problem involving Maxwell boundary conditions, where the accommodation coefficient can be a piecewise constant function on the boundary, allowing for more general bounded domains. Moreover, we develop a delicate application of the $L^2-L^\infty$ bootstrap argument, which relies on the specific geometry of our domains, to effectively handle this mixed-type boundary condition.

Boltzmann equation with mixed boundary condition

Abstract

We study the Boltzmann equation in a smooth bounded domain featuring a mixed boundary condition. Specifically, gas particles experience specular reflection in two parallel plates, while diffusive reflection occurs in the remaining portion between these two specular regions. The boundary is assumed to be motionless and isothermal. Our main focus is on constructing global-in-time small-amplitude solutions around global Maxwellians for the corresponding initial-boundary value problem. The proof relies on the hypocoercivity at the linear level, utilizing the weak formulation and various functional inequalities on the test functions, such as Poincaré and Korn inequalities. It also extends to the linear problem involving Maxwell boundary conditions, where the accommodation coefficient can be a piecewise constant function on the boundary, allowing for more general bounded domains. Moreover, we develop a delicate application of the bootstrap argument, which relies on the specific geometry of our domains, to effectively handle this mixed-type boundary condition.
Paper Structure (4 sections, 11 theorems, 228 equations)

This paper contains 4 sections, 11 theorems, 228 equations.

Table of Contents

  1. Introduction
  2. Preliminary
  3. $L^2$ estimate
  4. $L^\infty$ estimate

Key Result

Theorem 1

Assume $\Omega$ is bounded and smooth, where the boundary is given by bdr_portion. There is a constant $\delta>0$ such that if $F_0(x,v):=\mu+\sqrt{\mu}f_0(x,v)\geq 0$ satisfies $\int_{\Omega}\int_{\mathbb{R}^3}\sqrt{\mu}f_0(x,v)\,\mathrm{d} v\mathrm{d} x=0$ and then there exists a unique solution $f(t,x,v)$ to the problem f_eqn with the initial condition $f(0,x,v)=f_0(x,v)$ such that $F(t,x,v):=

Theorems & Definitions (23)

  • Theorem 1
  • Lemma 1: R
  • Lemma 2
  • proof
  • Lemma 3: Lemma 5 of G
  • Proposition 2
  • Remark 1
  • Lemma 4
  • Remark 2
  • Lemma 5: Bernou
  • ...and 13 more