Investigation of model validity for numerical survivability testing of WECs

This paper investigates the applicability of two numerical models to assess the survivability of Wave Energy Converters (WECs). Simulations using both a fully nonlinear Navier-Stokes solver (based on OpenFOAM) and WaveDyn (a linear time-domain model for multi-body interactions) are compared with physical experiments involving a free-floating buoy with a single mooring line. Events in which survivability is a concern are modelled using the focus wave-group NewWave. Two wave-groups (one steeper than the other) are used to identify the validity of each numerical model as a function of wave steepness. By taking into account the CPU cost and model validity, the range of applicability for both models is discussed. This constitutes the first step in future work: coupling the two numerical models to form an efficient modelling tool that benefits from the computational efficiency of WaveDyn while including the fidelity of a Navier-Stokes solver when required; therefore providing valuable information for WEC developers.