Experimental analysis of pulsatile flow effects on flow structure in transitional-type cavity

Studies combining flow separation and pulsatile flow phenomena are inherent in the field of biomedicine and have many engineering and biomedical applications. In this study, the pulsatile flow structure is investigated experimentally based on a transitional-type cavity with a length-to-depth ratio of 8 using a microparticle image velocimetry system. A pulsatile flow is generated by pulsating the inlet pressure in sinusoidal pulses using a pressure control unit. Stationary flow and four sets of pulsatile parameters are investigated: two pulsation am-plitudes (A = 0.15 and 0.60) and two pulsation frequencies (f = 0.5 and 1 Hz) in the Reynolds range of 50-2000. The recirculation flow dynamics in a cavity are analyzed by investigating the effect of pulsations on the flow structure and statistical flow parameters such as vorticity, shear rate, and turbulence intensity. The analysis shows that the effect of the pulsation amplitude on the recirculation zone dynamics is more prominent than that of the pulsation frequency. The magnitude of the recirculation zone reduction achieved by the pulsatile flow is inversely proportional to the pulsation amplitude. A reduction in the recirculation zone length decreases the shear rate distribution along the cavity. Additionally, an analysis into the turbulence intensity shows that effect of pulsations is negligible when the flow approaches the turbulent flow regime.