Stability of Couette flow for 2D Boussinesq system in a uniform magnetic field

TL;DR

This paper proves the nonlinear stability of Couette flow in a 2D Boussinesq magnetohydrodynamics system, introducing a novel Fourier multiplier to handle complex terms and demonstrating asymptotic and nonlinear stability.

Contribution

It introduces a new Fourier multiplier operator leveraging enhanced dissipation to prove stability of Couette flow in a magnetohydrodynamics context.

Findings

Proved asymptotic stability of the linearized system.

Established nonlinear stability using bootstrap argument.

Developed a novel Fourier multiplier for complex term control.

Abstract

In this paper, we consider the Boussinesq equations with magnetohydrodynamics convection in the domain $\mathbb{T} \times \mathbb{R}$ and establishes the nonlinear stability of the Couette flow $(\mathbf{u}_{sh} = (y,0), \mathbf{b}_{sh} = (1,0), p_{sh} = 0, \theta_{sh} = 0$). The novelty in this paper is that we design a new Fourier multiplier operator by using the properties of the enhanced dissipation to overcome the difficult term $\partial_{xy}(-\Delta)^{-1}j$ in the linearized and nonlinear system. Then, we prove the asymptotic stability for the linearized system. Finally, we establish the nonlinear stability for the full system by bootstrap principle.