Development and Verification of a Wave Energy Converter Simulation Tool

McComb, C. , Lawson, M. , and Yu, Y-H.

2013, Marine Energy Technology Symposium

Numerical simulations to predict the dynamics and performance of wave energy converters (WECs) are challenging, requiring the simulation of complex fluid-structure interactions between a WEC device and the wave environment. Full Navier-Stokes computational fluid dynamics (CFD) simulations coupled with a multi-body dynamics solver are an effective simulation tool for this purpose because the governing physics are modeled from first physical principles. Unfortunately, the computational resources required to perform these types of high-fidelity simulations are significant, precluding the use of CFD simulations for design optimization. One method for reducing the numerical complexity of WEC simulations is to model the hydrodynamics using a heuristic approach that uses hydrodynamic coefficients derived from frequency-domain simulations to model the relevant hydrodynamics, while simulating the motion of the WEC device in the time-domain. The primary objective of the work presented herein is to develop such a numerical tool using the multi-body 6-degree-of-freedom (6DOF) solver SimMechanics and the frequency-domain hydrodynamics code WAMIT. The numerical tool was developed so that WEC devices comprised of arbitrarily connected multiple bodies and various power-take-off (PTO) systems could be readily modeled in operational sea states. In addition, the tool was developed to allow non-linear PTO control strategies to be considered. Using the simulation tool described above, the effect of fluid memory on predicted power output is then investigated. This is accomplished through comparison of numerical results with and without fluid memory.