Separated turbulent flow over a small amplitude wave

Turbulent flow of water over a two-dimensional sinusoidal wave surface has been studied using laser-Doppler velocimetry. The amplitude-to-wavelength ratio of the wave was 2a/lambda = 0.125 and the Reynolds number was 13,200. For these conditions the flow on the downstream side of each wave was fully separated. Comparisons with experiments on a wave with 2a/lambda = 0.20 at the same approximate Reynolds number show that reduction in 2a/lambda results in a disproportionately larger reduction in the thickness of the recirculating zone.