A novel oscillating wave surge converter by hollowing out the flap bottom: Numerical studies using smoothed particle hydrodynamics

Abstract

Oscillating wave surge converters (OWSCs) have been extensively investigated. However, previous studies have mainly optimized their structural parameters, and the OWSC cost has seldomly been considered. The optimized OWSC may be uneconomical. Therefore, this study proposes an improved method by examining the fluid characteristics near the OWSC flap and by hollowing out the flap bottom. Such a design can not only enhance the OWSC, but can also save material making it economical. Furthermore, the capture factor (CF) per flap height (CFH) was proposed to evaluate the OWSC. The CFH considers a material cost that is positively correlated with flap height. The Sobol sensitivity analysis results show that only the wave period, water depth, power take-off system damping, flap hollow top height, and flap top height must be considered when optimizing the OWSC. This reduces half of the parameter dimensions to be optimized, further reducing the calculation cost and time. When optimizing the improved OWSC and the original OWSC to maximize the CFH, the CFH of the former one is 2.22 times larger than that of the latter, which indicates a significant improvement in OWSC economy. This implies that improved OWSC and CFH should be adopted in practical engineering applications.