Modeling of wave energy converters by GPUSPH and Project Chrono

Abstract

This study presents a fully coupled numerical approach to study wave energy converters interaction with water waves. The open-source Smoothed Particle Hydrodynamics model GPUSPH is used to resolve wave dynamics and compute the hydrodynamic force on wave energy converters. The dynamics of wave energy converter is computed by the open-source physics engine, Project Chrono. The capability of the coupled numerical model to handle wave-body interaction is validated by considering a floating body in still water. The results show that the coupled model correctly predicts the balance between the floating body weight and the buoyancy force. Furthermore, the effectiveness of density diffusion method in reducing acoustic noise in a weakly compressible SPH model is also justified. In addition, the model is validated by laboratory experiment on floating body interaction with nonlinear wave packet. The model is then applied to simulate two types of wave energy converters. We conduct a thorough study of GPUSPH modeling of surface-piercing oscillating wave surge converter under waves. GPUSPH accurately predicts both wave gauge measurements and the device rotation as recorded in the laboratory. By virtue of the Project Chrono library we examine the power take-off scenario of the oscillating wave surge converter by introducing kinematic constraint into the system. The device performance under storm condition is further examined. We further present and simulate a conceptualized catenary mooring wave energy converter device, CSI-Device, under real sea states. We not only examine the interaction of CSI-Device with waves, but also we obtain the mooring force on the device that can facilitate the design of wave energy converters. We show that to maximize the energy extraction, it is important to design the device to have a natural frequency similar to the wave period of deployment site to maximize the swing motion of the pendulum. Finally the interaction of CSI-Device under different sea states with both relatively small and large wave heights are evaluated by placing the device in a directional spectral wave basin. Overall, this study shows that the open-source model GPUSPH is an efficient tool for modeling wave energy conversion devices in directional nonlinear sea states.