Shock Wave Boundary Layer Interactions (SWBLIs) occur frequently in supersonic and hypersonic flows and, depending on the strength of the shock wave and the state of the boundary layer, may lead to boundary layer separation. This can result in a multitude of problems, such as an increase in drag, a drop in air intake efficiency and high fatigue loads due to the inherent unsteadiness of the ow phenomenon. Since a turbulent boundary layer has a better capability to withstand the adverse pressure gradient that is inherent to the incident shock wave when compared to a laminar boundary layer, it is beneficial to have a turbulent boundary layer at the interaction. By forcing boundary layer transition only a short distance upstream of the interaction, the capability of the boundary layer to remain attached is increased while retaining the low skin friction coefficient of a laminar boundary layer for as long as possible.

Micro-ramps are currently being investigated as a means of reducing negative effects of shock wave-turbulent boundary layer interactions. A micro-ramp enhances the mixing of the ow by introducing vortices in the ow, thus energizing the boundary layer to overcome the adverse pressure gradient due to an impinging shock. The effect of changing micro-ramp height, Mach number and Reynolds number on the mean ow downstream of a micro-ramp's center-line has been studied extensively.