Kelvin-Helmholtz instability in anisotropic viscous magnetized fluid

Kelvin-Helmholtz instability in anisotropic viscous fluid with uniform density in the presence of magnetic field is simulated through solving the non-ideal magnetohydrodynamic equations. The magnetic field is uniform and parallel to the stream. The magnetohydrodynamic equations are solved by corner transport upwind algorithm and constrained transport algorithm. In this paper, the influence of viscous anisotropy on Kelvin-Helmholtz instability is studied. The viscous anisotropy is embodied in the direction of the magnetic field, that is, viscosity parallel to the direction of the magnetic field line is much larger than that in the other directions. The results in the isotropic and the anisotropic viscous cases are compared from the aspects of flow structure, vortex evolution, and magnetic field distribution. It shows that the viscous anisotropy is more advantageous to the stability in a magnetized shear layer than the viscous isotropy. The flow structure evolves similarly in large scales but vortices evolve differently in small scales. Due to the decrease of the shear rate in the direction of the magnetic field lines, the rolling-up degree of interface and the number of laps decrease; the multiplication and merging of small vortices in the rolled-up structure destroy the regular growth of the vortex, which contributes to the stability of the flow. The increase of the magnetic energy at the sheared interface slows down effectively by the viscous anisotropy, which weakens the growth of the transverse magnetic pressure and anti-bending magnetic tension. However, viscous anisotropy shows much greater influence on the transverse magnetic pressure than on the anti-bending magnetic tension. The total enstrophy decreases slowly in viscous isotropy and anisotropy case. It increases quickly in late time in the former case, but is heavily suppressed in the latter case.