The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects

Details The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects

2004-03-04

arxiv.org/abs/astro-ph/0403125v1

Physics of Plasmas 10(12), 4661, 2003

Astronomy and Astrophysics

Astrophysics

Published in Physics of Plasmas, figures absent due to file sizes, full version at http://www.phys.uu.nl/~toth/ (follow Public

Scientific paper

10.1063/1.1624076

The Kelvin-Helmholtz (KH) instability occurring in a single shear flow configuration that is embedded in a uniform flow-aligned magnetic field, is revisited by means of high resolution two-dimensional (2D) magnetohydrodynamic (MHD) simulations. First, the calculations extend previous studies of magnetized shear flows to a higher compressibility regime. The nonlinear evolution of an isolated KH billow emerging from the fastest growing linear mode for a convective sonic Mach number $M_{cs}=0.7$ layer is in many respects similar to its less compressible counterpart (Mach $M_{cs}=0.5$). In particular, the disruptive regime where locally amplified, initially weak magnetic fields, control the nonlinear saturation process is found for Alfv\'en Mach numbers $4\simlt M_A \simlt 30$. The most notable difference between $M_{cs}=0.7$ versus $M_{cs}=0.5$ layers is that higher density contrasts and fast magnetosonic shocklet structures are observed. Second, the use of adaptive mesh refinement allows to parametrically explore much larger computational domains, including up to 22 wavelengths of the linearly dominant mode. A strong process of large-scale coalescence is found, whatever the magnetic field regime. It proceeds through continuous pairing/merging events between adjacent vortices up to the point where the final large-scale vortical structure reaches the domain dimensions. This pairing/merging process is attributed to the growth of subharmonic modes and is mainly controlled by relative phase differences between them. These grid-adaptive simulations demonstrate that even in very weak magnetic field regimes ($M_A \simeq 30$), the large-scale KH coalescence process can trigger tearing-type reconnection events previously identified in cospatial current-vortex sheets.

Affiliated with

Also associated with

No associations

Rating

The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The two-dimensional magnetohydrodynamic Kelvin-Helmholtz instability: compressibility and large-scale coalescence effects will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-590516