Simulation of Oceanic Wakes from Flow Around Offshore Wind Turbine Foundations and their Creation of Sediment Trails

Abstract

Offshore wind farms are a fast growing area of research, development and construction. Rapidly growing renewable energy sectors like offshore wind also need to have development plans in mind which are compatible with biodiversity protection and conservation efforts. One potential source of environmental strain is the generation of sediment trails in turbulent wakes downstream of monopile foundations. This is especially relevant for New Jersey, as construction of an offshore wind farm, Ocean Wind 1, has already begun. The goals of this study are to better understand the fluid mechanical mechanisms at hand which create turbulent wakes and trap sediment for long periods of time downstream of monopile foundations, and to determine possible ways to mitigate sediment trail generation. Six different simulations were run using LES, with varying depths and flow conditions which include, and neglect, the presence of shear from the ocean floor. It was largely observed that streamwise vorticity values from the models which included shear varied very little with the depth of the model. However, models with flow conditions which neglected shear saw large variations in streamwise vorticity with increasing depth. Additionally, locations of maximum and minimum vorticity in the model and mirror symmetry along spanwise dimensions support the potential for counter-rotating vortices on opposite sides of the foundation which could pick up and trap sediment from the ocean floor. Further research is needed to model the physical trapping of particles to validate this hypothesis. These results support the need for increased research and development of floating foundations, and the potential they have to mitigate sediment trail generation, while still providing immense sources of carbon-free energy.