On the numerical modeling and optimization of a bottom-referenced heave-buoy array of wave energy converters

Abstract

Compact arrays of small wave absorbers have been proposed as an advantageous solution for the extraction of wave energy when compared to a big isolated point absorber. Numerous challenges are associated with the numerical modeling of such devices, notably the computation of the hydrodynamic interactions among the large number of floats of which they are composed. Efficient calculation of the first-order linear hydrodynamic coefficients requires dedicated numerical tools, as their direct computation using standard boundary element method (BEM) solvers is precluded. In this paper, the Direct Matrix Method interaction theory by Kagemoto and Yue (1986) is used as an acceleration technique to evaluate the performance of a generic wave energy converter (WEC) inspired by the Wavestar SC-concept and to perform layout optimization. We show that there exists an optimum number of floats for a given device footprint. Exceeding this number results in a “saturation” of the power increase, which is undesirable for the economic viability of the device. As in previous studies on multiple absorber WECs, significant differences were observed in energy production among floats, due to hydrodynamic interactions.