Investigation of separation control in compressible boundary layers using periodic disturbances

The effect of compressibility on flow control by periodic blowing and suction in an adverse pressure gradient boundary layer is studied using direct numerical simulation based on the two- dimensional compressible Navier-Stokes equations. Previous work has shown that oscillating disturbances can reduce or eliminate separation, as well as weakening buffeting downstream of the separated region, both for separation bubbles and for massively separated flows. We examine the flow field for two Reynolds numbers, and for Mach numbers Ma = 0.3 and 0.6. For the low Reynolds number case we examine the development of instability waves, and show that their behavior can be modified by periodic forcing. For the high Reynolds number, the flow strongly separates and we show that flow control by periodic disturbances is effective at both Mach numbers.