Numerical calculations for accretion disks in close binary systems

A numerical method for 3D magnetohydrodynamical investigations of accretion disks in close binary systems is presented, which allows for good spatial resolution of structures (hot spot, accretion column). The gas is treated as individual gas cells (pseudo-particles) whose motion is calculated within a grid consisting of one spherical inner part for 3D MHD and two plane outer parts. Viscous interactions of the gas cells are taken into account by a special treatment connected with the grid geometry. The author presents one result of 2D hydrodynamical calculations for a binary applying the following parameters which are representative for Cataclysmic Variables: M1 = 1 solar mass, r1 = 10-2 solar radius, M2 = 0.5 solar mass, p = 0.2 d, dM/dt = 10-9 solar mass y-1. Column density and radiative flux distributions over the disk are shown and briefly discussed by comparison with the theoretical understanding of these Dwarf Novae drawn from observations. (Auth.)