A nonlinear critical layer in nonequilibrium gas

The method of matched asymptotic expansions is used to analyze the evolution of disturbances of a nonequilibrium compressible boundary layer on a flat plate in the region of nonlinear critical layer. A dispersion relation is obtained for low-amplitude subsonic disturbances. An equation is derived, which describes the evolution of disturbance in the nonlinear stage of its development. It is demonstrated that, similar to the case of equilibrium media, the increase in the disturbance amplitude in the given stage of development of turbulence exhibits an explosive pattern. The characteristic time of instability decreases with increasing degree of disequilibrium of the medium.