Multi-scale modeling of wind-wave interaction in the presence of offshore structures for renewable energy applications

We develop a multi-scale modeling capability for the simulation of wind and wave coupling dynamics, with a focus on providing environmental input for wind and wave loads on offshore structures. For the large-scale wind-wave environment, largeeddy simulation for the wind turbulence and high-order spectral simulation for the nonlinear ocean waves are dynamically coupled. For the local-scale air and water flows past the structure, we use a hybrid interface capturing and immersed boundary method. Coupled level-set/volume-of- fluid/ghost-fluid method is used to capture the wave surface. Immersed boundary method is used to represent the structure. The large-scale wind-wave simulation provides inflow boundary conditions for the local-scale air-water-structure simulation. Our simulation captures the dynamic evolution of ocean nonlinear wavefield under the wind action. The wind field is found to be strongly coupled with the surface waves and the wind load on a surface-piercing object is largely wave-phase dependent.