Flow visualization by velocity-pressure cross-correlation

For a better understanding of turbulent structure, a new flow visualization method of the time averaged structure of the turbulence has been developed by using wall pressure fluctuations to detect the velocity fluctuations of the flow. Velocity fluctuations were visualized by the measured velocity-wall pressure cross-correlation with the whole flow field for various time-delays between two measured values. Turbulence structures of a backward-facing step flow were investigated for three different flow regions-the recirculating flow just behind the step, the reattachment flow, and the boundary layer flow far down stream from the step. Sequential contour maps of cross-correlation values were calculated to display movement and deformation of turbulent structures both qualitatively and quantitatively.