Analytical Study On The Hydrodynamic Performance Of A Dual Pontoon Wave Energy Device In The Presence Of The Seawall

The integrated devices consist of wave energy converters and other types of marine structures have good application prospects for their multi-function and lower costs.It is crucial to study the hydrodynamic performance in the presence of coastal reflection for the floating wave energy devices applying in coastal waters.Motivated by the fact that coastal reflection affects the performance of the WEC significantly,in this paper,the wave extraction performance and attenuation performance of an interconnected floating breakwater-WEC device is investigated in the presence of the seawall.Based on linear potential flow theory,an analytical model is developed for a dual pontoon wave energy device in the presence of partially reflective seawall.The model is verified using wave flux conservation law and the Haskind relationship.The optimal PTO damping imposed on the device is deducted considering the changes of the vertical component of the interconnected point.The effects of structure and the coastal reflection parameters are being focused and the causes of the effects are illustrated.The main conclusions are as follows:1.The impact on the hydrodynamic performance of the main structural parameters are as follows.The results show that the system with smaller distance between two floats is shown to be more capable of capturing wave energy.The position of the hinge point has a significant impact on the wave power extraction performance and wave attenuation performance.The effective frequency bandwidth of the system can be extended by choosing a smaller float size.2.The coastal reflection parameters effect on the hydrodynamic performance of the device are studied.The capture width ratio(CWR),reflection coefficient,and transmission coefficient vary periodically as the distance between the breakwater and seawall increases.Regular oscillations can be found in the hydrodynamic parameters with the presence of coastal reflection and the oscillations become stronger as the coastal reflection increases.3.The influence on the narrow gap resonance between two floats by the coastal reflection is studied.The coastal reflection coefficient has no effect on the resonance wave height and resonance frequency in the narrow gap of two fixed box.However,it has a slight effect on the trend of the wave extraction performance and fluid resonance in the narrow gap.As the distance between the sidewall and the breakwater increases,the wave extraction performance and wave surface elevation in the narrow gap vary periodically.The gap resonance has a negative effect on wave extraction performance of the floating device applying to the waters with lower wave frequency.