Wave interaction with multiple submerged porous structures

Abstract

In the present study, two submerged porous structures under the action of ocean waves are analysed to understand the wave control performance due to porosity parameter. The studies in the first case consider the submerged porous structure kept at finite depth backed by rigid wall at a distance L. The second case explains the two submerged porous structures with sea wall. The numerical study is performed considering the velocity potentials in (i) open water region (seaside), (ii) porous region (primary porous structure), (iii) open water region (in between the porous structures), (iv) porous region (second porous structure) and (v) open water region (lee side). The linearized wave theory is used to analyse the wave interaction with submerged porous structures. The matching conditions are adopted based on continuity of mass and velocity, and the orthogonality condition is used to formulate the boundary value problem, and the eigenfunction expansion method is adopted for the determination of reflection, transmission coefficients, energy loss and wave forces on submerged porous structures. Numerical computation is performed for predicting the wave reflection and transmission from the submerged porous structures for different structure width and angle of incidence conditions. The existence of the porosity and friction causes energy loss and minimum friction; maximum porosity results in high wave transmission and less wave reflection. The significant difference is observed when submerged porous structure is divided into two submerged porous structures with rigid wall. In all the cases, the width of the porous structure is considered similar and is observed to play a predominant role in wave reflection, transmission and stability of the structure. The study will help in the novel economic design of the submerged porous structures for the protection of coastal facilities. © Springer Nature Singapore Pte Ltd. 2019.