NUMERICAL SIMULATIONS OF BLACK HOLE ACCRETION

A resume of fruitful interaction between analytical and numerical approach to the subjectof accretion disks around black holes is here presented. We review time dependent simulations of unviscous and moderately viscous accretion flows. Convection or pressure dominated flows admit subkeplerian solutions with or without shocks. The viscous adiabatic solutions, however, don't match smoothly to the keplerian disk solutions. We show also that many different type of mechanisms can trigger quasi periodic oscillations of the flow and consequently of the emitted radiation.