Aleksei M. Fridman

From hydrodynamical instability to turbulent viscosity in accretion disks

The existence of a spiral‐vortex structure is revealed by a numerical simulation of the dynamics of an accretion disk in close binary stars. This structure is a density wave containing a one‐armed spiral and an anticyclonic vortex with the center at a corotation radius, where the azimuthal phase velocity of the wave coincides with the angular rotation velocity of the disk. The formation of the structure is caused by an over‐reflection instability rather than the tidal influence of a companion star. Similar instability generates the observed one‐armed “mini‐spiral” in the innermost central part of the Galaxy located inside 1.5 pc. The over‐reflection instability results in a turbulence of the accretion disk. A value of turbulent viscosity coefficient is in accordance with both, the value of a numerical viscosity in presented calculations, and the results of observations. The period of the density wave rotation is in agreement with the typical periods of light curve variations observed in cataclysmic binary...