Hydrodynamics study on rectangular porous breakwater with horizontal internal water channels

Abstract

A novel concept of a hybrid floating breakwater-windbreak structure is proposed to shield vulnerable coastal regions from both extreme wave and wind loads in storms. A porous design was adopted for the breakwater part of the structure with the view to improving its hydrodynamic performance. The porosity was achieved by having horizontal internal water channels in the breakwater for free passage of water through the breakwater body. The wave response of such a floating structure is first investigated by analytical solution and then partially compared with laboratory model tests. A CFD analysis was performed to investigate the sidewall effects in the model tests. The horizontal wave forces and wave elevations in the vicinity of the floating breakwater with and without internal water channels were measured experimentally and compared so as to assess the effect of the water channels. The results show that the water channels help to reduce the lateral wave excitation force which is advantageous to breakwaters held in position by mooring dolphins/caissons. At the same time, the floating breakwater efficiency was maintained since the porosity did not increase in the wave transmission coefficient.