Wave-turbulence interaction may contribute to momentum and energy transfer in the near-surface region beneath water waves. However, the nature and extent of this mechanism have not been well understood. A wave separation technique was developed to study quantitatively the momentum and energy transport due to wave-turbulence interaction. In this technique a nonlinear stream function representation of the wave motion was determined so as to satisfy the kinematic and dynamic boundary conditions at the water surface. Wave-induced velocities were then deduced from the stream function and subtracted from measured velocity components to obtain the turbulent flow field. This technique was applied to laboratory data taken beneath wind-generated water waves. Coherence spectra indicate high correlation between turbulence and wave-induced motions at some frequencies. Time-averaged correlations between wave and turbulent velocities increase with wind speed and decrease with increasing distance away from the interface. Although there is no significant momentum transfer due to wave-turbulence interaction, this mechanism results in significant energy transfer among the mean, wave-induced, and turbulent flow fields.
Journal of Geophysical Research
- Pub Date:
- September 1990
- Oceanography: Physical: Surface waves and tides;
- Oceanography: Physical: Turbulence;
- and mixing processes