A revisit to the large-time behavior of the Vlasov/compressible Navier-Stokes equations

TL;DR

This paper analyzes the long-term dynamics of coupled kinetic-fluid equations, showing exponential alignment of particle and fluid velocities, and improves previous results by refining assumptions using a new Lyapunov functional.

Contribution

It establishes the exponential alignment in the large-time limit for the Vlasov and compressible Navier-Stokes system, refining previous results with a new analytical approach.

Findings

Exponential alignment of velocities over time

Refined assumptions for large-time behavior

Introduction of a new Lyapunov functional

Abstract

We establish the large-time behavior for the coupled kinetic-fluid equations. More precisely, we consider the Vlasov equation coupled to the compressible isentropic Navier-Stokes equations through a drag forcing term. For this system, the large-time behavior shows the exponential alignment between particles and fluid velocities as time evolves. This improves the previous result by Bae-Choi-Ha-Kang[Disc. Cont. Dyn. Sys. A, 34, (2014), 4419--4458] in which they considered the Vlasov/Navier-Stokes equations with nonlocal velocity alignment forces for particles. Employing a new Lyapunov functional measuring the fluctuations of momentum and mass from the averaged quantities, we refine assumptions for the large-time behavior of the solutions to that system.