  We investigate the problem of self-gravitating dust disk dynamics in a static
state taking into account nonlinear effects. For this purpose Schrodinger-type
equation including the mass conservation law is used for the whole description
of hydrodynamic flows of self-gravitating dust. We have shown a purely
hydrodynamic mechanism of ring formation in the radial direction by taking into
account nonlinearity in the lowest order of expansion parameter, which
determines an order of magnitude of flow.
