Abstract
The existing instability theories can not treat evolutional and equilibrium processes of alternate bars because of the linear theory. The purpose of this work is to clarify the stabilization mechanism of bars in equilibrium and to estimate dominant wave length and bar formation conditions based on the derived nonlinear solutions. The theoretical dominant wave length is obtained by the condition that wave steepness of equilibrium bar becomes maximum. This dominant wave length is almost identical to that by the linear theory. The formation region becomes narrower than that by the linear theory, but the former still provides a good explanation for the formation region of alternate bars.
