Hydrodynamic investigation of a parabolic breakwater for wave energy focusing

Abstract

The integration of wave energy converters (WECs) with a breakwater can reduce construction and maintenance costs and enhance the energy conversion performance of WECs. Intelligent use of a parabolic breakwater to focus water waves to a specific region can significantly increase the available wave energy. However, the theoretically calculated focal point of a parabolic breakwater may not always coincide with the observed wave focusing position. To determine the actual position of the focal point for installing the WEC, both numerical simulations and experimental research are conducted to investigate hydrodynamic characteristics of the parabolic breakwater. The realized focal point is found to be located at a position separated from the theoretical position, and its location varies with the incident wavelength. The underlying cause of this behavior is identified and investigated. The effects of chord length, parabolic wall aspect ratio, and incident wave directions on the wave amplitude at the focal point are examined. It is found that the shift in the actual focusing position exhibits a cyclic configuration as the incident wavelength changes, with the observed focal point revolving around the theoretical focal point. The position of the recorded focal point is determined by the interaction between the incident and reflected wave crests. The wave amplitudes at the theoretical focal point reaches their maxima when the focal lengths are nearly equal to integer multiples of half incident wavelength. The wave amplitudes at both the theoretical and observed focal points are shown to magnify with increasing chord length and with decreasing focal length. The parabolic wall is demonstrated to consistently maintain a substantial focusing effect for incident wave angles up to 15°.