A NESTED GRID REFINEMENT TECHNIQUE FOR MAGNETOHYDRODYNAMIC FLOWS

A grid refinement technique for high resolution magnetohydrodynamical flows is described. It is based on the use of multiple nested grids ha ving successively higher resolution. The numerical algorithm is formul ated in such a way that the advection part of the hydrodynamical equat ions are solved in conservative form on the whole integration domain. In particular, the divergence free constraint for the magnetic field, del . B = 0, is fulfilled during the simulation. Several numerical tes ts are presented demonstrating the applicability of the nested grid co de to many astrophysical problems including phenomena in which steep g radients such as shocks or contact discontinuities appear.