Seabed influence on wave scattering by a porous flexible barrier in a two-layer oblique sea.

The interaction between an oblique gravity wave and a partial porous flexible plate barrier in a two-layer fluid with an undulating bottom has been studied using small amplitude and structural response theory. Separate cases for (a) scattering of wave and (b) trapping of wave by porous flexible plate in the presence of an impermeable sea wall are discussed. The submerged plate of two typical configurations, bottom standing and surface piercing, is considered. The effects of surface waves, interfacial waves, and the induced energy among the layers due to undulated bottom have been taken into consideration. An approximation technique, i.e. modified mild-slope equation and the Fourier method together with the method of least-square, is adopted as a solution procedure. By applying the continuity condition and mass flux at the interface along with the plate boundary conditions, the problem is converted into a system of equations. Different physical characteristics are investigated, including reflection and transmission coefficients, wave load on the plate and impermeable sea wall, and bottom effect against parameters like incident wave angle and bottom slope length. This study finds that bottom-standing plate dissipated much surface wave energy, whereas the surface-piercing plate dissipates much interfacial wave energy. An opposite effect of surface and interfacial waves on membrane deformation for any given bottom, with maximum deformation due to propagating wave along surface and interface for plane and sinusoidal bottoms, respectively, is observed. The influence of undulated sea bottom on surface wave generated force upon sea wall is almost insensitive, whereas interfacial wave-induced force on sea wall varies significantly with changing bottom profiles. The study carried out in this article holds good potential in deepening our understanding of wave scattering and trapping by a partial porous flexible barrier. [ABSTRACT FROM AUTHOR]