Performance Characteristics of an OWC in Regular and Random Waves

Typically, the dimensions of OWC chamber have a single resonant frequency which captures efficiently wave energy over a narrow range of frequency of the waves. The high-frequency waves are reflected. Provision of a pair of additional harbour walls in front of the device creates an added resonance enabling it to capture substantial energy from a wider range of frequency of the waves. Although, there exists a substantial loss in energy due to wave deformation as the wave from the offshore approach shallow waters, in which case, the harbour walls prevent any further dissipation till it reaches the device. This chapter reports the influence of
harbour walls on the hydrodynamic characteristics of a bottom - mounted OWC. The study was carried out with different configurations of harbour walls, i.e., the projecting length was varied in terms of the ratio of harbour wall length (c) to the breadth of OWC (b), (c/b = 1, 1.5 and 2). The opening angle of harbour wall was varied in the range of [π/2, 7π/8] in an interval of π/8 with respect to the front lip wall of OWC. The results reveal that the efficiency of the OWC with the harbour walls has been significantly improved. The details of such a behaviour are herein discussed.