Turbulence Effect on Wall Pressure Fluctuations

Oncoming turbulence plays a prime role in determining the pressure fluctuation on the upwind face of a structure. Along this face a forward stagnation highly turbulent three-dimensional boundary layer, i.e., a forward wake-like flow, develops. The turbulence, which can markedly amplify through the stretching of cross vorticity, includes a vortex flow pattern near the wall. These vortices impart their energy directly to the wall pressure fluctuations. This is substantiated by the observed consistent, remarkably similar variation of wall pressure fluctuations power spectra and turbulence-energy spectra upstream of the windward wall. The transfer of energy is affected by turbulence-turbulence and turbulence-mean shear interaction mechanisms. Wall pressure fluctuations are particularly dependent upon large-scale turbulence characteristic of forward stagnation flow.