Wave power extraction from a U-shaped oscillating water column consisting of a flexible bottom-standing front wall

In this paper, the concept of a U-shaped oscillating water column (UOWC) device consisting of a flexible bottom-standing front wall is proposed. The deflection of the flexible wall could bring benefits for wave power absorption. To evaluate the hydrodynamic performance and predict the wave power absorption of the flexible UOWC, a theoretical model based on the linear potential flow theory and the Galerkin approximation method is developed. For some examined flexible UOWCs, three peaks of the frequency response of the maximum wave power capture efficiency are observed, in which two are related to the resonant frequencies of the oscillating water column and the 1st natural mode of the flexible wall, respectively, and one could be related to wave near-trapping. The flexural rigidity of the flexible bottom-standing front wall is found to be a key factor affecting the performance of the device. As the dimensionless flexural rigidity increases, the three peaks of the efficiency-wave frequency curve move toward large frequencies and a large bandwidth of high efficiency is achieved.