Wave interaction with a two-layer porous breakwater in the presence of step-type bottom阶梯式底面下两层多孔防波堤与波浪的相互作用

Oblique wave interaction with a two-layer breakwater consisting of perforated front and back wall in the presence of bottom undulations is analyzed. Wave characteristics are studied in the framework of small-amplitude wave theory, and Darcy’s law is used for flow past porous structures. The varying bottom topography spanned over a finite interval connected by two semi-infinite intervals of uniform water depths. Eigenfunction expansion method is used to handle the solution in the regions of uniform bottom and a modified mild-slope equation along with jump conditions is employed for varying bottom topography. Reflection, transmission, and wave energy dissipation coefficients are obtained numerically by applying the matrix method to understand the effects of several physical quantities such as wavenumber, porosity, and angle of incidence. The transmission coefficient reduces significantly and the wave energy dissipation is high for the present model. Also, Bragg scattering is analyzed in the presence of step-type rippled bottom and presented in this paper.