Wave field with a submerged porous breakwater

Abstract

The flow field of linear waves passing a submerged porous breakwater has been solved analytically in this paper. The permeable breakwater is considered to be aniso‐tropic but homogeneous. The hypothesis of equivalent work is assumed in the porous field to ensure the existence of velocity potential in an irrotational flow field. The boundary value problem is then solved by the method of separation of variables. The eigenvalues in the boundary value problem with porous media are in general, complex. There are two series solutions of eigenvalues in the water column containing the porous breakwater. The range of each mode of eigenvalues, even in porous media, has been given explicitly. Orthogonality of the velocity potentials has been proved and the convergence of the series solution verified. The corresponding flow field has then been studied by varying wave and structure properties and justified by experiments. Since wave reflection can occur on both sides of the porous breakwater, partial standing waves, as well as a resonance, similar to harbor seiche, may be found in the corresponding flow region.