THE GENERATION OF PEAK PRESSURES IN SEPARATED/REATTACHING FLOWS

Abstract An experimental study was conducted to investigate the occurrence of large negative peak pressures near the leading edge of sharp-edged bluff bodies. Flow visualization experiments with a long flat plate reveal that negative peak pressures are produced when the separated shear layer rolls up to form a large vortex near the surface. The largest peaks occur approximately 0.25X R from the leading edge where X R is the mean reattachment length. Intermittent roll-up of the shear layer occurs in smooth flow as well as in turbulent flow for a model with a long afterbody. Conditional sampling of pressure data increases spanwise correlation length scales. Limited data obtained with a two-dimensional square cylinder with front face normal to the flow demonstrate the importance of accurately modelling turbulence intensity scale in wind tunnel studies of buildings.