New problems in the theory of the supersonic flow stability

The stability theory of supersonic viscous flows was formulated by Lees, Lin and Dunn. Their stability equations are mainly for parallel flows of a perfect gas. Before the sixties the investigations were based on the integration of the stability equations. Only the first (subsonic) mode was investigated. Now numerical methods are used for the stability analysis of the various parallel flows and the problem of the supersonic boundary layer stability in Lees-Lin-Dunn formulation has been solved. Together with the classic stability theory the new directions of the linear disturbances development in the supersonic flows are worked out now. This paper discusses three of these problems