  We present the results of systematic comparison of 2D and 3D numerical models
of mass transfer in semidetached binaries. It is shown that only for case of
\gamma \sim 1 (near-isothermal case) the obtained 2D and 3D solutions are
qualitatively similar. For higher value of \gamma the 3D flow structure is
drastically changed and for \gamma=1.2 the accretion disk is not formed in the
system. Numerical results show that for case of \gamma=1.2 the 2D and 3D
solutions are different. We discuss the spiral-shaped shock waves obtained in
numerical models. It is shown that these shocks are not intrinsic spirals and
are caused by collisions of the gaseous flows in the system.
