Electronic edition ISSN 1574-0579

Collisional Kelvin--Helmholtz instability in a magnetized fluid

S. Ranjbar Deliri-Aghdam - M. Hosseinpour - M. Moslehi Fard

Faculty of Physics, University of Tabriz, 29 Bahman Blvd, Tabriz, 16471, Iran

Abstract
Kelvin-Helmholtz instability (KHI), driven by velocity shear, significantly alters the 6 large-scale dynamics of conductive fluids in space and laboratory settings, including the solar corona, astrophysical jets, Earth's magnetopause, and Tokamak devices. Using 2D resistive magnetohydrodynamic (MHD) simulations, we examine how uniform resistivity influences the magnetic-energy amplification during KHI in a compressible plasma under a uniform stream-aligned magnetic field. Resistivity is varied over four orders of magnitude. We find that, until a characteristic time, magnetic energy grows primarily through the work performed by the flow on the magnetic field, especially during the linear and early nonlinear stages of the instability. This flow work is most effective near the boundaries of the developing KHI vortices, where the magnetic field generation is consequently strongest. At KHI transitions into fully developed turbulence, Ohmic dissipation balances the flow work, leading to magnetic energy saturation. Sporadic magnetic reconnection events, triggered by KHI in the turbulent regime, are shown to be key mechanisms for dissipating and converting magnetic energy within intense current sheets. Tables 2, Figs 6, Refs 24.