A finite-element study of the efficiency of arrays of oscillating water column wave energy converters

Prior research on wave energy devices such as Oscillating Water Column (OWC) systems has revealed the complex nature of the interactions between ocean waves and these systems. This is especially true when such devices are arranged in arrays. Within these arrays, the multiple scattered waves produced by each device interact and can lead to unexpected fluctuations of the power captured by each individual OWC. In the present study, a finite element model based on linear wave theory has been developed to study scattered waves around single and multiple oscillating water column wave energy conversion devices. The power capture efficiency of a single cylindrical OWC deduced from the finite element model is compared with the numerical approximation used by Evans and Porter (1997). The efficiency of the single OWC is then compared with that of an array of OWCs of the same dimensions, as a function of array spacing, pneumatic damping and direction of the incident waves. It is found that the presence of neighboring OWCs has a significant influence on the power capture efficiency of individual devices, even for large separations, and that the optimal pneumatic damping for OWCs in an array may differ from that of an isolated OWC of the same dimensions.