SHAPE OPTIMIZATION DESIGN OF A HEAVING BUOY OF WAVE ENERGY CONVERTER UNDER BIMODAL SPECTRAL WAVES NEAR ISLANDS AND REEFS

Wave Energy Converters (WECs) have been developed to advance marine energy technologies towards commercialization. The choice of geometrical shape for WECs is of great importance for increasing energy capture. The characteristics of wave spectrum will be provided with bimodal characteristics when waves propagate from deep water area to the area near the islands and reefs. This variation of the wave spectrum must be considered for the optimization of the WECs placed near islands and reefs. Nevertheless, no standard and consistent method has been established for this purpose yet. The novelty of the present study lies in optimizing the shape of a WEC for maximizing its mean annual absorbed power under bimodal spectral waves when using a flexible geometry definition, such as FFD method. The optimization object is based on a heaving buoy that considers a linear PTO system. The objective of the optimization is to maximize the mean annual absorbed power. The optimization process is proposed by using NSGA-II. A numerical analysis framework based on potential flow theory is presented for determining the mean annual absorbed power under bimodal spectral waves. The results obtained using this method significantly improve the computational efficiency compared to those using CFD method. Thus, this paper provides a guidance for the design of the optimization of the heaving buoy under bimodal spectral waves.