Response Of Turbulent Fluctuations To The Periodic Perturbations In A Flow Over A Backward Facing Step

There is a great amount of interest in the flow over a backward facing step where the sep-arated flow re-attached to the wall forming a well-defined separation region.Here in this inves-tigations zero-net-mass-flux control jet was applied to the field, different actuation frequencies and strengths were studied.In the experiment we used the multi-phase smoke-wire visualization, particle image ve-locimetry,infrared thermography and pressure tap to collect and analysis the flow.It was found that the actuation frequency near the flapping frequency of the shear layer made prominent different as from higher actuation frequencies. Near the shedding frequency of the vortex in the shear layer,the mean pressure at bottom wall near the step and the reattachment length reached a minimum value,meanwhile the heat transfer rate of the bottom wall showed a maximum value. In the locations near the step, some parameters of the flow showed linear relation to the actuation strength.It can be used in the build of the mathematical model.