How local thermodynamics, viscosity and stellar-mass-ratio influence the whole structure of accretion disc in close binaries: 3D SPH simulations.

Abstract. Physical turbulent viscosity in an accretion disc involves an enhanced radialmass and angular momentum transport in high compressibility conditions. However, asticking e ect throughout the disc, a ects the low compressibility disc’s dynamics. Pairsof compressibility-viscosity values, together with initial kinematic conditions at the innerLagrangian point, can define a well-bound accretion disc, whilst other pairs cannot producesuch well-bound structures. In this work, the role of the stellar mass ratio M 1 = M 2 (SMR)between the compact primary and the companion in a close binary system (CB) is alsotaken into account. Results show that such role is essential in modifying domains whereparameters compressibility-viscosity-injection velocity at L1 allow a well defined disc con-sistency. The higher the SMR M 1 = M 2 , the wider the domain where the accretion disc showsa well-bound consistent structure. Key words. Accretion: Accretion Discs – Methods: Numerical – Stars: Close Binaries –Stars: Dwarf Novae