Global regularity for solutions of magnetohydrodynamic equations with large initial data
Xiangsheng Xu
TL;DR
The paper studies global regularity for the incompressible magnetohydrodynamic equations in $\mathbb{R}^N$ with large initial data ($N\ge3$). It develops a De Giorgi-type iteration to obtain an $L^\infty$ bound for $w=|u|^2+|b|^2$ by combining scaling, interpolation, and a Calderón–Zygmund bound on the pressure, leading to a priori estimates independent of the time horizon. A key consequence is the existence of a global-in-time strong solution and a quantitative bound $\|w\|_{\infty,Q_T}\le 32\|w(\cdot,0)\|_{\infty}+c\|w\|_{L_N,Q_T}^{s_5}$, which in particular implies global regularity in the Navier–Stokes case $b\equiv0$. The methodology provides a robust framework for proving global regularity for nonlinear parabolic systems by blending three ingredients: scaling, interpolation, and De Giorgi iteration.
Abstract
We study the regularity properties of solutions to the initial value problem for the magnetohydrodynamic equations in $\mathbb{R}^N, N\geq 3$. We obtain a global in-time strong solution without any smallness assumptions on the initial data.
