Nonlinear interfacial motion in magnetohydrodynamic flows

Nonlinear motion of vortex sheets with non-uniform current is investigated taking the magnetohydrodynamic Richtmyer–Meshkov instability (MHD RMI) and the magnetohydrodynamic Kelvin–Helmholtz instability (MHD KHI) as the examples. As the ratio of the magnetic force to the convective force increases, Alfven oscillations appear and the nonlinear growth of the interface as a vortex sheet is suppressed. We show that the turbulent energy possessing the interface flows into the magnetic energy, which causes the strong magnetic field amplification for both instabilities. We also discuss the difference of the temporal evolution of the interface between MHD RMI and MHD KHI.