A Nonlinear Computational Model for Floating Wind Turbines

The dynamic motion of floating wind turbines is studied using computational simulations. The full three-dimensional Navier-Stokes equations are solved on a regular structured grid, using a level set method for the free surface and modified immersed boundary method to model the turbine platform. The tethers, the tower, the nacelle and the rotor weight are include using reduced order dynamic models, resulting in an efficient numerical approach. Wind is modeled as a constant thrust force. Other aerodynamic loading, rotor gyroscopic effects, and aeroelastic effects are not considered in the current study. The response of a tension leg platform to moderate amplitude waves is examined. By using the current approach, nearly all the nonlinear and viscose effects can be considered while keeping the computational cost reasonable. The model is applied to a Tension Leg Platform (TLP) consisting of a ballasted cylindrical tank.