HYDRODYNAMIC CALCULATIONS OF ACCRETION DISKS IN CLOSE BINARIES - THE SUPERHUMP PHENOMENON

We have calculated the hydrodynamic evolution of an accretion disc in a close binary system with a low mass ratio in order to study the supe rhump phenomenon. We have tested the mode-coupling model of Lubow (199 1a, 1991b) and find simular results if only the m = 3 component of the tidal potential is used during the simulations. In case the full pote ntial of the companion star is used, no eccentric prograde accretion d isc evolves. The effective disc radii we infer from our simulations ar e approximately 70% of the Roche radius. These accretion discs are too small to become eccentric via the model of Lubow.