On stability of Poiseuille flow in a channel with surface ribbing

The stability of Poiseuille flow in channels with walls grooved in the streamwise direction is investigated numerically. In the framework of physically-grounded scalings of velocity and length an analysis of energy and linear critical Reynolds numbers was carried out in a practically important range of rib heights, sharpness, and spacing. It was shown that there are such values of these parameters that both critical Reynolds numbers are higher than those for the plane channel.