Scaling effects on the damping of wave energy converters

The efficient operation of wave-energy converters requires a resonance between the natural frequency of the devices and the frequency of incoming waves. However, the power delivered at resonance is controlled by the damping. Thus, experiments were undertaken on the effects of size change on the internal damping of small-scale converter models. Two of the most popular concepts for wave energy conversion were examined: the heaving buoy and the oscillating water column. It was found that the damping contributions traditionally not considered by linear wave theory exert a significant, nonlinear impact on the damping as model-size is varied.