##
Tidally-Driven Transport in Accretion Disks in Close Binary Systems

Blondin, John M.
*Published in:*
NewA, 5, 53

### Abstract

The effects of binary tidal forces on transport within an accretion disk are
studied with a time-dependent hydrodynamical model of an
isothermal accretion disk. Tidal forces quickly truncate the accretion disk to
radii of order half the average radius of the Roche lobe, and
excite a two-armed spiral wave that remains stationary in the rotating reference
frame of the binary system. We measure an effective alpha
of order 0.1 near the outer edge of the disk in all of our models, independent
of the mass ratio, Mach number, and radial density profile.
However, in cold disks with high Mach number, the effective alpha drops rapidly
with decreasing radius such that it falls below our threshold
of measurement (0.001) at a radius of only one third the tidal radius. In warmer
disks where the Mach numbers remain below 20, we can
measure an effective alpha down to radii 10 times smaller than the maximum size
of the disk.