Towards Numerical Simulation of Offshore Wind Turbines Using Anisotropic Mesh Adaptation

Abstract

In the context of reducing the cost of floating wind energy, predicting precisely the loads applied on structures and their response is essential. As the simulation of floating wind turbines requires the representation of both complex geometries and phenomena, several techniques have been developed. The wake generated by the aerodynamic loads experienced and the tower can be modeled using methodologies inherited from onshore wind simulation, and coupled with a hydrodynamic codes that were most of the time developed for the oil and gas industry. This work proposes a methodology for the simulation of a single or several turbines with an exact representation of the geometries involved, targeting an accurate evaluation of loads. The software library used is ICI-tech, developed at the High Performance Computing Institute (ICI) of Centrale Nantes. A single computational mesh is used, where every phase is defined through level-set functions. The Navier–Stokes (NS) equations are solved in the Variational MultiScale (VMS) formalism using finite element discretization and a monolithic approach. A coupling with an automatic and anisotropic adaptation procedure guarantees the good representation of the geometries immersed. The adaptation allows the simulation of phenomena with very different orders of magnitude, e.g. aerodynamics around blades and waves propagation. The reduction of the number of points in the mesh and the massive parallelization of the code are also necessary for wind turbine simulation.