Efficiency of an oscillating water column device in front of a vertical breakwater

In the present paper an analytical model is presented for the three - dimensional wave diffraction and pressure - radiation problems of an OscillatingWater Column (OWC) device in front of a vertical breakwater of infinite length. The analysis is based on the linearized velocity potential representation, the image theory and the matched axisymmetric eigenfunction expansion formulations. The hydrodynamic interactions among the device and the adjacent breakwater are exactly taken into account. Detailed insight into the device's loads, due to the wave impact and the inner air pressure distribution in the chamber, is given, as well as, the air volume flow and the air pressure in the chamber of the OWC in front of the vertical wall are outlined. The main goal of the paper is to examine the effect of the breakwater on the efficiency of the OWC device, presenting the absorbed wave power by the device with and without the presence of the breakwater, supplemented with representative numerical results.