Velocity measurements for a turbulent nonseparated flow over solid waves

The laser-Doppler velocimeter was used to obtain measurements of the streamwise velocity over solid sinusoidal waves of small enough amplitude that a nonseparated flow existed. The measurements provide a critical test for Reynolds stress closure models since they are particularly sensitive to happenings in the viscous wall region (y ⁺ < 40), for which present theories are of uncertain accuracy. The results are compared with calculations that use an eddy viscosity model that successfully describes measurements of the wall shear stress along waves of small enough amplitude that a linear response is obtained. These calculations are in approximate agreement with measurements because they exactly account for inertia and viscous effects. However, there are significant differences which point to the inadequacy of turbulence models. In particular, non-linear effects and the amplitudes of the wave-induced velocity variations are underpredicted.