Wave Attenuation due to Stratified Porous Structure with Stepped Seabed

The wave interaction with stratified porous structure combined with a surface-piercing porous block in a stepped seabed is analysed based on the small amplitude wave theory. The study is performed to analyse the effectiveness of partial porous structure in increasing the wave attenuation in the nearshore regions consisting of stratified porous structures of different configurations using the eigenfunction expansion method and orthogonal mode-coupling relation. The hydrodynamic characteristics such as wave reflection coefficient, transmission coefficient, dissipation coefficient, wave force impact and surface elevation are investigated due to the presence of both horizontally and vertically stratified porous structures. The effect of varying porosity, structural width, angle of incidence, wavelength and length between the porous block and stratified structure is examined. The numerical results are validated with the results available in the literature. The present study illustrates that the presence of the stratified structure decreases wave transmission and efficient wave attenuation can also be easily achieved. The wave force acting on stratified structure can be decreased if the structure is combined with wider surface-piercing porous blocks. Further, the presence of stratified porous structure combined with porous block helps in creating a tranquil zone in the leeside of the structure. The combination of vertical and horizontal stratified porous structure with surface-piercing porous block is intended to be an effective solution for the protection of coastal facilities.