Simulations of Stratified Turbulent Flow over Moving Waves

The surface layer of the atmospheric marine PBL is frequently thermally stratified, which further compounds our difficulty in understanding small scale air-sea interaction mechanisms. In order to explore the interaction between stratified turbulence and water waves, we have conducted a series of direct and large-eddy simulations of stratified Couette flow over prescribed moving surface waves. Simulation results will be presented that highlight the interaction between waves and stratified turbulence. Mean profiles, turbulence statistics, flow visualization, and form stress variations will be shown as function of wave age and stratification. In this study both unstable and stable stratification will be considered. One of the new results we have found is that the signature of the waves is more pronounced in stably stratified flows. In addition, we will compare these new results with our prior simulations of neutrally stratified flow.