Numerical simulations of the Kelvin-Helmholtz instability in magnetohydrodynamics

BILBAO, L.; GRATTON, F. T.

Mendoza, Argentina

Congreso; FLUIDOS-2006, IX Reunión sobre Recientes Avances en Física de Fluidos y sus Aplicaciones; 2006

Facultad de Ingeniería, U N Cuyo

A Finite Volume, Arbitrary Lagrangian-Eulerian, code for magnetohydrodynamic flows is described. The code is aimed to the study of the non linear evolution of the Kelvin-Helmholtz (KH) instability in 3D+t for local models of planar stratified boundary layers. The numerical scheme, programming features, and examples of applications to vortex formation in supersonic magnetohydodynamic flows are shown. The computational method starts from the integral conservative form of ideal, one fluid, compressible, magnetohydrodynamics, but the design is modular so that several other physical mechanisms can be introduced, like resistivity and viscous tensor among others, that have been programmed in separated parts, switched-off at the present stage of the investigation. The computational box is set with periodic boundary conditions in the two directions normal to the main flow, and permits the study of results either with periodicity in the third direction, or the possibility of free flows at the downstream exit. The program can simulate the development and saturation of the magnetohydrodynamic KH instability from an initial configuration of stratified laminar flow. It can also study the response of the boundary layer to driven perturbations, like the arrival of permanent oscillations of finite amplitude generated upstream. The code has been used to examine the formation of vortices in models of the equatorial boundary layer of the terrestrial magnetopause. Work supported by the Argentinean grants UBACYT X206/04, X291/04, and CONICET PIP 5291/05, PIP 2217.