  The structures of plasma flows in close binary systems whose accretors have
strong intrinsic magnetic fields are studied. A close binary system with the
parameters of a typical polar is considered. The results of three dimensional
numerical simulations of the material flow from the donor into the accretor
Roche lobe are presented. Special attention is given to the flow structure in
the vicinity of the inner Lagrangian point, where the accretion flow is formed.
The interaction of the accretion flow material from the envelope of the donor
with the magnetic field of the accretor results in the formation of a
hierarchical structure of the magnetosphere, because less dense areas of the
accretion flow are captured by the magnetic field of the white dwarf earlier
than more dense regions. Taking into account this kind of magnetosphere
structure can affect analysis results and interpretation of the observations.
