The Role of Pressure-Velocity Correlation in Oscillatory Flow Between a Pair of Bluff Bodies

Turbulent flow measurements were conducted between two bluff bodies set in uniform flow in tandem arrangement. The velocity obtained with PIV were averaged with respect to either time or phase of periodic pressure oscillation induced by vortex shedding from the bluff body, i.e., Reynolds decomposition or three-level decomposition. The Reynolds stress caused by periodic fluid motion was found excessively large compared with those related to turbulent fluctuation in entire flow field. The PIV data were used to solve discrete Poisson equation of instantaneous pressure. The effect of organized vortex motion was recognized as the strong correlation between velocity and pressure gradient, which could explain the poor performance of RANS turbulence models in predicting this kind of flows.