Multiphysics simulations of the dynamic and wakes of a floating Vertical Axis Wind Turbine

A framework performing Large Eddy Simulations of the flow past Floating Offshore Vertical Axis Wind Turbines (FOVAWT) mounted on semi-submersible platforms is presented. The simulation tool captures the unsteady flow and the resolved 6-DOF motion of the system. A state-of-the-art vortex particle-mesh method solves the aerodynamics and wakes of the turbines. The hydrodynamic loads are accounted for via the relative form of the Morison's equations while the mooring lines tension is computed through a lumped-mass model. Realistic conditions are further obtained by introducing a sheared turbulent inflow and erratic waves in a simulation domain that extends ten diameters downstream of the machine. First, analyses of an isolated FOVAWT wake and motion are performed and the impact of prominent environmental phenomena is assessed. In a second step, the interactions of two FOVAWTs throughout their wakes are studied. In general, the incoming wake signature induces larger oscillation of the downstream machine, alters the shape of the wakes and shortened the transition to turbulence.