Control reattachment of backward-facing step flow using a row of mini-jets in recirculation bubble

In this experimental study, we introduce an open-loop control method for shortening the reattachment length in a backward-facing step flow using a row of pulsatile min-jets in the recirculation bubble. The mini-jet perturbations are imposed in two ways, i.e., in-phase perturbation and traveling-wave perturbation. Both types of perturbations are found to shorten the reattachment length, while the former is more effective and gives comparable extent of the length reduction as the mini-jets imposed at the step separation point. The change in the flow field by the perturbations is unraveled on embedded coherent flow structures. Published under an exclusive license by AIP Publishing.