Three-dimensional effects on the performance of multi-level overtopping wave energy converter

The performance of a multi-level overtopping wave energy converter has been numerically investigated in a three-dimensional wave tank. The device has three extra slots and is positioned on a breakwater. The span length of the breakwater is the main parameter associated with the three-dimensional effects on the hydraulic efficiency of the wave energy device. It has been shown that the device with a finite span yields a lower captured crest energy due to waves falling-down the edges during the run-up process. The result also implies that as the span of the device is increased, the efficiency tends to increase further to resemble the two-dimensional device. The three-dimensional mechanism has a significant influence on the potential energy in the water being stored by the higher reservoirs, while that of lower ones have relatively smaller effects. In addition, a relation between hydraulic efficiencies of two and three-dimensional devices has been proposed.