Design and hydrodynamic study of a new pile-based breakwater-OWC device combined system

In order to enhance the conversion efficiency and optimize the hydrodynamic performance of the OWC device, a novel combined system composed of a pile-based OWC chamber and a perforated wave-eliminator is proposed. The schemes with rectangular front wall M1, elliptical front wall M2, M3 are designed. Physical tests and numerical simulations were conducted for the hydrodynamic process under the action of wave of the system with H/d = 0.16, 0.20, 0.24 and L/B = 3.3, 3.8, 4.3, 4.7, 5.2, 5.5, 6.4. The obtained-results show that the system has better energy converting and wave eliminating performance than the other existing systems. Its maximum conversion efficiency ξ is up to 70%, while its transmission coefficient Ct is less than 0.45. Compared to M1 and M2, M3 can improve the efficiency ξ of the system (up to approximately 35%) and reduce the maximum force exerted on the system (up to 10%). When studying the forces on the combined system, the horizontal force (in the direction of wave propagation) can be primarily calculated by considering the force exerted on the chamber. However, when investigating the vertical forces (opposite to gravity) acting on the system, both the OWC chamber and the wave-eliminator need to be considered. The research results can provide valuable references for further design optimization of OWC devices. •A novel OWC- breakwater combined system was proposed.•The energy conversion and wave dissipation effect were studied.•The force and flow flied characteristics were analyzed.•The effect of wave elements on system performance was considered.•The efficiency is up to 0.7, max-transmission coefficient is less than 0.45.