Performance of a submerged flexible membrane and a breakwater in the presence of a seawall

Abstract

In the present study, the performance of a submerged flexible porous membrane placed at a finite distance away from a partially reflecting seawall is investigated. Further, the membrane is floating over a porous breakwater which is bottom-standing in nature. The associated physical problem is solved using a numerical tool based on the dual boundary element method. Various physical quantities of interests such as the reflection coefficient, run-up coefficient, horizontal wave force acting on the seawall, and the maximum deflection coefficient of the membrane are studied for a variety of membrane, breakwater, and seawall parameters. The results demonstrate that the resonating behavior of the aforementioned physical quantities diminishes with the introduction of structural porosity in the membrane wave barrier. Further, the membrane having moderate width is effective in reducing the wave run-up in the lee side of the membrane for a broader range of incident wave frequencies. Moreover, the reflection coefficient, run-up coefficient, and wall force coefficient decrease in a nonlinear manner as the wavelength of the incident waves becomes shorter. The combined flexible membrane and rubble mound breakwater system can effectively create a tranquility zone in the lee side of the membrane wave barrier.