Wave Scattering by Submerged Porous Disk

Abstract

Linearized potential wave theory is applied in the present paper to investigate the phenomenon of wave scattering by a submerged porous disk. By means of the eigenfunction expansion method, harmonic expressions of the velocity potential in terms of unknown constants are obtained in two subregions of the domain by taking into account the boundary conditions on the free surface, the porous disk surface, and sea bottom surface, as well as the Sommerfeld condition at infinity. These unknown constants are then determined by the matching conditions. Variation of the wave height around the disk and the wave load on the disk versus the dimensionless disk radius, the relative water depth, and the porous‐effect parameter is discussed. It is found that the wave scattering by a disk includes a process of focusing wave energy near the rear of the disk for small dimensionless porous‐effect parameters. An increase of the dimensionless porous‐effect parameter decreases the wave height, and the behavior of a porous disk is similar to that of a wave absorber that may lead to setdown for a large disk radius.