Accurate prediction of the motion of a wave energy converter and the loads acting on it is of great significance in the design procedure. In this work, the interaction between focused waves and a hemispherical-bottomed buoy is simulated using the in-house CFD solver naoe-FOAM-SJTU. The time histories of three focused waves at several positions are presented and compared with experimental data from the CCP-WSI working group. The effects of wave steepness on motion responses of the hemispherical-bottomed buoy and the loads in the mooring system are presented and discussed.


Under extreme wave conditions, strong non-linear impact phenomena such as severe wave run-up, relative motion and green water may occur, which will cause a large local impact load on wave energy converters (WECs). Exploring interaction between waves and WECs have great importance for the design and protection of WECs. So accurate prediction of the motion of a WEC and the loads acting on it is of great significance in the design procedure. Numerous researchers have done experimental and numerical studies on this problem.

Previously, Savin et al. (2012) experimentally measured lateral force acting on the funnel under two sea states. Two measurements were taken by two separate measuring systems with slightly different timing. The development of the method could be used for evaluation of the forces from waves acting on the WEC. Azimuth-inclination angles and snatch load on a tight mooring system are mainly discussed in their work. Hann et al. (2015) concerned experimental measurements of the interaction of a taut moored floating body, representing a WEC in survivability mode, with extreme waves. Focused wave groups, based initially on NewWave theory, were used to generate the extreme waves, with crest amplitude exceeding the mooring's design capacity. They discussed the influence of wave steepness effect on model response and mooring load using a focused wave groups. Goteman et al. (2015) considered the survivability of a 1:20 scale point-absorbing WEC model in extreme wave tests with focused waves embedded in regular waves and irregular waves. Experimental results of the forces were presented. Mai et al. (2016) performed experiments to examine wave-structure interactions for a series of simplified FPSO-shaped bodies.

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