Mitigation of wave force on a tunnel in the presence of submerged porous plate over trench-type bottom topography

Abstract Thin porous plates serve as an effective model for the construction of breakwater. Thus, the problem involving oblique wave interaction with a tunnel in the presence of a submerged horizontal porous plate over a trench-type bottom is investigated. In this paper, for the mathematical formulation of the physical model, water wave potentials are defined using Havelock's expansions and flow past over porous structure is modelled based on Darcy's law. The advantage of the trench type of bottom and horizontal plate are studied through the numerical results of forces on the tunnel. The study reveals that more energy loss and less force on the tunnel are obtained if the porous effect parameter of the plate or the length of the plate is increased up to a moderated value of these parameters. Compared to the case without porous plate and trench-type bottom topography, there are significant changes in forces due to this porous breakwater and trench-type bottom topography. In addition, from the present results, it may be noted that the load on the submerged tunnel is reduced by adding a submerged horizontal porous plate and asymmetric trench, which is helpful in understanding the role of porous breakwaters and trenches in applications to Ocean and Coastal Engineering.