Gravity wave interaction with a porous breakwater in a two-layer ocean of varying depth

Abstract Oblique gravity wave interaction with a thick porous breakwater is analyzed in a two-layer ocean having bottom undulation. The plane-wave solution in water of constant depth is matched with the solution of mild-slope equation in the region of varying depth. The breakwater is assumed to be extended from free-surface to seabed. Two different physical aspects such as (i) wave scattering and (ii) wave trapping by porous breakwater near an impermeable wall are investigated. Reflection and transmission coefficients due to interaction of surface and interfacial waves with the breakwater are analyzed for parameters associated with waves, breakwater and seabed profiles. In this study, it is found that porous breakwater reduces transmission considerably in surface and interfacial waves for bottoms over which more wave transmission occurs at lee side. Wave reflection is found to be zero remarkably at some incident angles, depth ratios and bottom topographies. Distance between wall and breakwater is optimized to attain less force on wall The present study will enhance the understanding of scattering and trapping of waves from a porous breakwater under wave–wave interaction in a two-layer ocean of continental shelf. The findings are likely to be useful for creation of tranquility zones and protection of coasts.