Influence of Impermeable Elevated Bottom on the Wave Scattering due to Multiple Porous Structures


Department of Applied Mechanics and Hydraulics National Institute of Technology Karnataka, Surathkal, Mangalore – 575025, India


The significance of multiple porous structures with finite spacing upon elevated seabed in the presence and absence of the leeward wall is examined under oblique wave impinging. Fluid propagation is assumed over the impermeable elevated bottom, and the fluid realm is separated into open water and porous structure regions. Continuity of the dynamic pressure and mass fluxes at the interfaces of the porous structure and the open water regions are adopted. The resistance and reactance due to the presence of the porous structure are taken into account using the porous structure dispersion relation. The numerical model is developed based on the eigenfunction expansion method along with matched velocity potentials at the interfaces of open water and the porous block regions. The wave reflection and transmission characteristics, energy damping and wave force impact on the leeward wall is analysed. The significance of the porosity, structural width, angle of incidence, width between the two structures and water chamber length is studied considering multiple porous blocks with finite spacing under oblique wave impinging in the presence and absence of leeward wall. The numerical results obtained in the present study agrees well with the theoretical and experimental results available in the literature. The present study illustrates that, with the increase in the number of porous blocks and gap between the porous blocks, the resonating trend is observed in the wave transformation and the influence of the elevated step height is revealed for the wave trapping.