Title: Simulating the Boundary Layer between a White Dwarf and Its Accretion Disk
Abstract: We describe the results of numerical simulations of the dynamics of the boundary layer (BL) between the accretion disk and the surface of a nonmagnetic white dwarf (WD) for different viscosities that correspond to different stages for dwarf novae burst cycles. The simulations cover the inner part of the accretion disk, the BL, and the upper atmosphere of the star. The high-viscosity case, which corresponds to a dwarf nova in outburst, shows an optically thick BL that after 1 Keplerian rotation period (tK = 19 s) extends more than 30° to either side of the disk plane. The BL is optically thick and thus occludes part of the star. The low-viscosity case, which corresponds to a dwarf nova in quiescence, also shows a BL, but it is optically thin.