Study of vortical separation from an axisymmetric hill

Surface mean pressures, oil-flow visualizations, and three-velocity-component laser-Doppler velocimeter measurements are presented for a turbulent boundary layer of thickness δ over an axisymmetric hill of height H=2δ. Complex vortical separations occur on the leeside and merge into two large streamwise mean vortices downstream. At x/H=3.69, the near-wall flow (y+<90) is dominated by the wall, while the vortices in the outer region produce large turbulence levels near the centerline and appear to have low frequency motions that contribute to turbulent diffusion.