Abstract
Wave concentrators have significant value for ocean energy absorbers to reduce power generation costs. Besides, the protection problem of the concentrator itself should also be carefully considered. In this study, a self-protected energy concentrator (SPEC) for water waves consisting of several truncated cylinders arranged in a concentric circle is proposed by adopting the cloaking technology based on the idea of manipulating scattered waves. To design the SPEC, an optimization program built by a combination of the higher-order boundary element method, the wave interaction theory, and the real-coded genetic algorithm is utilized. To address the manipulation mechanism of the scattered waves as well as to investigate the performance of the SPEC against various wave steepness and a spectrum of waves, the scattered waves and the total waves both inside and outside the concentrator are numerical and experimentally analyzed. High energy density inside the concentrator and the self-protection of the concentrator are validated. It is found that the large wave steepness can reduce the efficiency of concentration and self-protection due to the wave breaking. The SPEC has a high performance at a moderate bandwidth. Besides, the wave frequencies perform a more significant effect on self-protection than the concentration characteristic.