Evolution of the OrszagTang vortex system in a compressible medium. I. Initial average subsonic flow
Abstract
In this paper the results of fully compressible, Fourier collocation, numerical simulations of the OrszagTang vortex system are presented. The initial conditions for this system consist of a nonrandom, periodic field in which the magnetic and velocity field contain X points but differ in modal structure along one spatial direction. The velocity field is initially solenoidal, with the total initial pressure field consisting of the superposition of the appropriate incompressible pressure distribution upon a flat pressure field corresponding to the initial, average Mach number of the flow. In these numerical simulations, this initial Mach number is varied from 0.20.6. These values correspond to average plasma beta values ranging from 30.0 to 3.3, respectively. It is found that compressible effects develop within one or two Alfvén transit times, as manifested in the spectra of compressible quantities such as the mass density and the nonsolenoidal flow field. These effects include (1) a retardation of growth of correlation between the magnetic field and the velocity field, (2) the emergence of compressible smallscale structure such as massive jets, and (3) bifurcation of eddies in the compressible flow field. Differences between the incompressible and compressible results tend to increase with increasing initial average Mach number.
 Publication:

Physics of Fluids B
 Pub Date:
 November 1989
 DOI:
 10.1063/1.859081
 Bibcode:
 1989PhFlB...1.2153D
 Keywords:

 Compressible Flow;
 Magnetohydrodynamic Flow;
 Magnetohydrodynamic Turbulence;
 Subsonic Flow;
 Vorticity;
 Computational Fluid Dynamics;
 Flow Velocity;
 Magnetic Field Reconnection;
 Magnetoacoustic Waves;
 Magnetohydrodynamic Waves;
 Spectral Energy Distribution;
 Plasma Physics