Global Well-posedness of Incompressible MHD System with Density-dependent Viscosity in ℝ2
Abstract
We study the Cauchy problem for the two-dimensional inhomogeneous incompressible Magnetohydrodynamic equations with density-dependent viscosity and vacuum. For initial data with positive mass, finite second moment of density, and zero total momentum, we establish the existence and uniqueness of global strong solutions when the viscosity is sufficiently close to one in L∞. The smallness threshold may depend on the initial data, while no separate smallness condition is imposed on the initial velocity or magnetic field. We obtain uniform-in-time bounds for the density second moment and its H1∩ W1,q norm, where q>2. Moreover, for every η∈(0,1), |√ρu(·,t)|L2+|b(·,t)|L2 decays at the rate t−η/2, and the H1 norms of ∇ u, P, and ∇ b decay at the rate t−(1+η)/2. The proof combines a velocity decomposition based on Hardy-space estimates with magnetic-field integrability and time-weighted energy estimates.
Related
- Global solutions to the two-dimensional compressible MHD equations with density-dependent bulk viscosity
- Efficient second-order physics-preserving schemes for incompressible flows with variable density and viscosity
- A well-posedness theory for the 2D inhomogeneous incompressible Euler equations and a class of global-in-time solutions
- Global Well-Posedness for Planar Compressible Magnetohydrodynamics with Degenerate Viscosity on Unbounded Domains
- Compressible Euler equations with time-dependent damping in the critical regularity setting: global well-posedness and strong relaxation limit
BibTeX
@misc{wang2026global,
title = {{Global Well-posedness of Incompressible MHD System with Density-dependent Viscosity in $\mathbbR^2$}},
author = {Xue Wang},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03182},
eprint = {2611.03182},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03182},
}
RIS
TY - UNPB
TI - Global Well-posedness of Incompressible MHD System with Density-dependent Viscosity in ℝ^2
AU - Xue Wang
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03182
UR - https://arxiv.org/abs/2611.03182
AB - We study the Cauchy problem for the two-dimensional inhomogeneous incompressible Magnetohydrodynamic equations with density-dependent viscosity and vacuum. For initial data with positive mass, finite second moment of density, and zero total momentum, we establish the existence and uniqueness of global strong solutions when the viscosity is sufficiently close to one in L^∞. The smallness threshold may depend on the initial data, while no separate smallness condition is imposed on the initial velocity or magnetic field. We obtain uniform-in-time bounds for the density second moment and its H^1∩ W^1,q norm, where q>2. Moreover, for every η∈(0,1), |√ρu(·,t)|_L^2+|b(·,t)|_L^2 decays at the rate t^−η/2, and the H^1 norms of ∇ u, P, and ∇ b decay at the rate t^−(1+η)/2. The proof combines a velocity decomposition based on Hardy-space estimates with magnetic-field integrability and time-weighted energy estimates.
ER -