On the Yudovich solutions for the ideal MHD equations
arXiv:1401.6326
Abstract
In this paper, we address the problem of weak solutions of Yudovich type for the inviscid MHD equations in two dimensions. The local-in-time existence and uniqueness of these solutions sound to be hard to achieve due to some terms involving Riesz transforms in the vorticity-current formulation. We shall prove that the vortex patches with smooth boundary offer a suitable class of initial data for which the problem can be solved. However this is only done under a geometric constraint by assuming the boundary of the initial vorticity to be frozen in a magnetic field line. We shall also discuss the stationary patches for the incompressible Euler system and the MHD system. For example, we prove that a stationary simply connected patch with rectifiable boundary for the system is necessarily the characteristic function of a disc.
40 pages