Suppression of low-frequency unsteadiness in shock wave–turbulent boundary layer interactions with a micro-bump

We propose a novel flow-control strategy to suppress low-frequency unsteadiness in shock wave–turbulent boundary layer interactions. Our analysis reveals that the breathing motion of the separation bubble is governed by the leading two-dimensional global mode through a modal resonance mechanism, with its growth rate primarily concentrated in a narrow region near the shock foot. By introducing a micro-bump at this critical location, we achieve targeted stabilisation of the global mode, resulting in a substantial attenuation of the low-frequency breathing motion. Consequently, the turbulent kinetic energy and wall-pressure fluctuations associated with the breathing motion are reduced by 85 % and 70 %, respectively. This study demonstrates an effective and precise approach for controlling low-frequency unsteadiness in shock-induced separation, while minimally disturbing the flow.