  Results of calculations of the flow structure in binary systems with mass
exchange driven by stellar wind are presented. 2D simulations have been carried
out using the Roe-Oscher scheme. The fine grid we used allowed us to detect the
details of the flow structure. In particular, it was found out that solutions
with the wind velocity V of the order of the orbital velocity of the system Vs
are unstable: in solutions with V<Vs -- the steady accretion disk takes place
and if V>Vs -- the cone shock forms. Consideration of the minor variations of
the wind velocity V around Vs shows that they can influence greatly the flow
structure causing transition from disk accretion to the accretion from the
flow. During the flow rearrangement period (the accretion disk destruction) the
accretion rate increases in dozens times for a short time (~0.1 of the orbital
period of the system). This change can result in the drop-off of the gas from
the accretor that is usually associated with activity in these systems.
