  We present results of numerical modeling made for the galactic stellar and
stellar-gas disk embedded in the spherical halo and bulge. The stellar disk is
simulated by N-body system, the equations of hydrodynamics are solved by
TVD-method. We used TREEcode-algorithm for calculation of a self-gravity in
stellar and gaseous components. The possibility of bars birth in a hot stellar
disk because of gravitational instability of a cold gas component is
investigated. The conditions of occurrence lopsided-galaxies from a
axisymmetric disk as a result of gravitational instability are explored. The
self-consistent models of double bars are constructed and the dynamical
stability of these structures is discussed.
