Velocity spectra for turbulent boundary layers on a concave surface

Spectra of u, v, and uv fluctuations in flat and concave turbulent boundary layers are compared. Additional insights as to the effects of concave curvature on turbulence structure are obtained from mean velocity and turbulence data, as well as from flow-visualization results. Major effects of concave curvature are to amplify the low-frequency, large-scale eddies and to produce large-scale roll cells. This broadens the energy-containing frequency range of turbulence, especially for the v fluctuations in the middle part of the boundary layer, and contributes to the high values of the correlation coefficient, R(uv). Spectra at Y(+) of 13 and 20 indicate that curvature does not significantly alter turbulence structure near the wall.