Optimal strategy of the asymmetric wave energy converter survival in extreme waves

Abstract

Enhancing the survival performance of wave energy converters (WECs) in extreme wave conditions is crucial, and reducing wave loads is a key aspect of this. Placing the device underwater has been recognized as a beneficial strategy, yet the determination of the optimal submerged depth and the effects of varying wave conditions remain ambiguous. To address this, the study numerically analyzes the total forces in both horizontal and vertical directions, along with their harmonic components, across different wave configurations. A computational fluid dynamics method is employed to investigate a triangular-baffle bottom-shaped oscillating floater, which is known for its high energy conversion efficiency. The findings indicate that submerging the device to a depth equivalent to half the actual focused amplitude (1/2Ab) is the most effective strategy in the given sea state, offering superior wave force reduction vertically and robust performance horizontally. The analysis of harmonics reveals the significant contribution of high-order components to the total wave forces. Additionally, the study examines the impact of focused wave amplitudes and peak frequencies, showing that although force reductions are lessened in more extreme conditions, the optimal submerged depth of 1/2Ab still yields near 30% reduction in total vertical force and 22% in total horizontal force. This research provides theoretical insight that can guide the enhancement of WECs' survival capabilities in practical engineering applications.