Hydrodynamic improvement of wave energy converter (WEC)'s performance tends to reach a bottleneck in that it becomes difficult to further jump over the present low-efficiency stage. Instead of focusing on conventional geometry or layout optimization of WECs, this study investigates an alternative way to overcome the efficiency challenge. Inspired by a parabolic reflector that can reflect sound towards a focal point, this study explores the concept of breakwater with parabolic openings to converge propagating waves toward a focus position. The wave energy harvest can be increased when a buoy-type WEC is set at the focus position. A 3D numerical wave tank based on the boundary element method is developed to investigate the wave field around this parabolic breakwater. It is confirmed that reflected waves from the parabolic opening of the breakwater can travel towards a fixed focus position. The maximum wave height of the full wave field appears at a location half, or one wave length away from the vertex of the parabolic opening. For a specified wave environment, the wave height at the focus position can reach over four times the incident wave height, indicating wave energy multiplication. Effects of the neighbouring openings' distance on the wave field are also investigated. As this distance increases, the maximum wave height at the focus position decreases accordingly. Further, the wave field around a parabolic breakwater with its focus inside or outside the parabolic opening area is discussed. It is recommended to design the breakwater with its focus position located inside the parabolic opening area. Finally, a truncated circular cylinder as a simplified buoy-type WEC is placed at the focus position of each parabolic opening in front of the breakwater. Compared with the conventional design, the heave response of the buoy in front of the parabolic breakwater can be amplified by about three times.
- Novel breakwater with parabolic openings is proposed for wave energy harvest.
- Wave height at the focus position can reach four times incident wave heights.
- Wave energy harvest of buoy-type WECs can be multiplied effectively.
- D numerical wave tank is developed to verify its hydrodynamic performance