Hydrodynamic analyses of multiple porous plates attached to the front of a vertical composite breakwater

Abstract

Based on the dual boundary element method, hydrodynamic performance analyses including the wave transmission, reflection, dissipation, forces, and moments were conducted on a vertical composite breakwater comprising a submerged rubble-mound breakwater with a vertical wall affixed to its top with horizontal porous plates. These analyses were performed over a wide range of relative water depths, horizontal plate configurations, horizontal plate quantities, widths, porosities, and plate depths of immersion and inclinations. The effects of altering the immersion depth of the vertical barrier and the submerged rubble-mound breakwater height were also investigated. Adding more horizontal plates to the vertical wall was found to help reduce wave transmission, energy dissipation, horizontal wave force, and wave-induced moments; however, this also increased the vertical wave force. Further, increasing the horizontal plate's relative width from 0.25 to 1.0 did not reduce the wave transmission significantly; this also reduced the horizontal wave force considerably, albeit at the expense of increasing the vertical wave force. Based on the results, a medium porosity of approximately 20% is recommended for the horizontal plates to ensure the optimal overall performance. Notably, the results of this study are expected to be useful for the optimal designs of this type of wave barrier.