Global small solutions to a special $2\frac12$-D compressible viscous non-resistive MHD system

TL;DR

This paper establishes the global existence and stability of solutions for a special 2.5-dimensional compressible viscous non-resistive MHD system near a steady state, using Besov space techniques and leveraging magnetic field effects.

Contribution

It introduces a novel approach exploiting magnetic field effects to prove global well-posedness for a challenging 2.5D MHD system without magnetic diffusion.

Findings

Global solutions constructed in Besov spaces with oscillating initial data

Enhanced dissipation due to background magnetic field observed

Optimal decay rates obtained for certain initial data

Abstract

This paper solves the global well-posedness and stability problem on a special $2\frac12$-D compressible viscous non-resistive MHD system near a steady-state solution. The steady-state here consists of a positive constant density and a background magnetic field. The global solution is constructed in $L^p$-based homogeneous Besov spaces, which allow general and highly oscillating initial velocity. The well-posedness problem studied here is extremely challenging due to the lack of the magnetic diffusion, and remains open for the corresponding 3D MHD equations. Our approach exploits the enhanced dissipation and stabilizing effect resulting from the background magnetic field, a phenomenon observed in physical experiments. In addition, we obtain the solution's optimal decay rate when the initial data is further assumed to be in a Besov space of negative index.