Numerical simulation of the breakwater-ramp design for multistage-overtopping wave energy breakwater hybrid device

Abstract

Multistage-overtopping wave energy device is an example of the overtopping concept in extracting energy from the ocean wave. The multistage opening allows the wave to overtop and stored inside the multistage reservoirs and later used for electricity generation. Previously, using concentrated V-shape-ramp on the conventional multi-reservoir Sea Slot-Cone Generator (SSG) has been proven to improve up to 67 percent in hydraulic power at the 3.5 meters of significant wave height and 9.3 meters of wave period. However, the performance begins to drop when operating at smaller wave height consisting of 2.5-meter significant wave height and 7.9 seconds of wave period. Thus, this follow-up paper presents a numerical study to improve device performance, especially at small wave height. Five breakwater-ramp designs were tested consisting of Basis, Design 1 to Design 5. The overtopping device performance was simulated using FLOW-3D CFD software. Results are presented in the form of mean overtopping discharge or potential energy stored and the total energy potential for each propose breakwater-ramp design. The numerical results show that the highest total energy potential represents as the potential power output is recorded by Design 4 and Design 5 with 63.26 and 63.05 kW respectively, compared to basis SSG device with only 29.14 kW at the wave height of 2.8 meters and a wave period of 9.3 seconds.