The Magnetohydrodynamic Richtmyer-Meshkov Instability: The Oblique Field Case

Abstract

The Richtmyer-Meshkov instability (RMI) occurs when a perturbed interface separating fluids with different densities is impulsively accelerated, typically by a shock wave [1, 2]. Fig. 1(a) shows the canonical situation where the RMI occurs. The effect of the instability on the interface is shown in Fig. 1(b): it has become highly distorted, which can lead to significant mixing between the two fluids. When the fluids involved are in the plasma state, the RMI can be affected by a magnetic field [3]. This can clearly be seen by comparing Fig. 1(b), which shows simulated postshock- interaction density contours when no magnetic field is present, and Fig. 1(c), which shows the result of an identical simulation carried out in the presence of a normal magnetic field. The observed suppression of the instability in this case is caused by changes to the shock refraction process at the interface with the application of a magnetic field that leave the interface vorticity free [4].