Internal wave generation from ocean current turbine operation

Internal waves are formed when the turbulent wakes from submerged objects such as Ocean Current Turbines (OCT), collapse under a stable density stratification. The resulting waves can propagate in multiple directions, interact nonlinearly with other internal waves. In addition, OCT-generated internal waves will transport significant energy fluxes over large distances and produce substantial turbulent mixing when they break. We have developed numerical simulations to study the dynamic processes involved in the formation of internal waves from submerged OCT systems. Our investigation was expanded to include the effects of the Richardson number, and ambient turbulent intensity (TI), for OCTs operating in a stratified environment. Different density profiles were investigated, while turbines in the LES simulations were modeled using a Blade Element model. From the simulations, the critical bulk Richardson number for the formation of the IGWs was determined. Furthermore, by increasing the turbulent intensity, the formation of IGWs from OCT operation is enhanced.

This work was supported by the Coastal Studies Institute's North Carolina Renewable Ocean Energy Program.