Influence of the lateral wall velocity on three-dimensional disturbance development in plane Poiseuille–Couette flow

The linear stage of three-dimensional disturbance development in the Poiseuille–Couette flow in the case when both walls can move in the lateral direction is investigated by applying the asymptotic triple-deck theory. It is shown that the lateral wall velocity has no effect on the streamwise velocity of a wave packet. The packet does not bifurcate, but drifts in the lateral direction at the speed equal to the arithmetic mean of the walls’ speeds. Characteristic “ripples” in the lateral direction are observed at the stage of packet formation.