CFD simulation of a Passively Controlled Point Absorber Wave Energy Converter

Paper in proceeding, 2018

Recently CorPower Ocean AB presented laboratory tests of a point absorber wave energy converter equipped with a novel technique for passive phase con- trol. The technique, known as WaveSpring, widens the response bandwidth by a negative spring arrangement, and in the tank experiment an up to three-fold in- crease in delivered power as compared to pure linear damping was observed. As previously reported, for point absorbers close to resonance the use of standard radiation-diffraction models can become unreliable while CFD simulations ac- curately captures the nonlinear wave height dependent response. Thus, in the present study a module representing the WaveSpring technology was implanted in the OpenFOAM framework and CFD simulations of the buoy were per- formed both with and without the WaveSpring module. Good agreement be- tween simulated and experimental results was observed, and the WaveSpring behavior was well captured in the numerical simulation. The CFD model can be used for further tuning of the WaveSpring/buoy design as well as providing val- idation data for radiation-diffraction models.