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Wave flow evolution against oscillating wave surge converters

The Oscillating Wave Surge Converter (OWSC) is one of the most promising operating devices that use wave energy conversion technology. This device consists of a surface-piercing flap rotating around a hinge fixed to the sea bottom. Such a pitching motion, combined with a hydraulic Power Take-Off (PTO), captures the energy from ocean waves. The efficiency of the wave energy conversion is dependent on the pitch amplitude and frequency. Meanwhile, the incident wavefield is changed due to the interaction with the flap. The changed wave flow is significant, as OWSCs are normally arranged in arrays. In other words, the wave flow associated with an OWSC can have significant impacts on the efficiency of its neighbour devices. Therefore, simulating and analysing the wave flow evolution is of great importance to optimise the arrangement of OWSC devices, while to date it has not been studied in detail. Based on OpenFOAM, this work examines the relationship between incident waves and the perturbed fluid field in proximity to the flap. To achieve this, one OWSC geometry is placed in a numerical wave tank, and its pitch movement is handled using the overset-mesh technique, which allows high-amplitude rotations. In addition, the PTO is implemented based on a spring-damping theory and the best coefficients were identified following validation against experiments. Subsequently, the flow evolution was analysed in a series of wave conditions. It was found that the wave disturbance is highly related to incident wavelength, and incident waves can be strengthened or weakened at certain areas – this will facilitate the optimisation of OWSC array arrangements.