Features of the linear stage of the development of 3D disturbances in the plane Poiseuille-Couette flow

Within the framework of the triple-deck theory, the linear stage of the development of three-dimensional disturbances in the Poiseuille-Couette flow was investigated. Numerical computations revealed "ripples" developing in the side direction in the initial phase of the linear stage. As in the case of two-dimensional disturbances, an increase in the relative velocity of the walls leads to the splitting of disturbances into two wave packets, of which the first grows faster and moves at a higher velocity. The disturbances propagate within a certain angle range.