Wall Pressure Fluctuations in a Turbulent Boundary Layer over a Bump

Direct numerical simulations of a turbulent boundary layer over a bump were performed to examine the effects of surface longitudinal curvature on wall pressure fluctuations. Turbulence statistics and frequency spectra were examined to elucidate the response of wall pressure fluctuations to the longitudinal curvature and to the corresponding pressure gradient. Wall pressure fluctuations were significantly enhanced near the trailing edge of the bump, where the boundary layer is subjected to a strong adverse pressure gradient. Large-scale structures in the wall pressure fluctuation distribution were observed to grow rapidly near the trailing edge of the bump and convect downstream. In addition, the distance between the streamwise vortices and the wall increased slightly near the trailing edge of the bump. This caused the magnitude of the streamwise vorticity to increase significantly due to the diminishing of the interaction with the wall, leading to an enhancement of the wall pressure fluctuations.