Three-Dimensional Model of Waves Passing Submerged Porous Structures

In this paper a three-dimensional model of waves passing submerged porous structures is presented. The boundary element method is used to describe flows in the porous structure and waves passing above the structure. Linear wave theory is used to describe the wave fields, and the theory of waves in the porous structures proposed by Sollitt and Cross (1972) is used for the porous structures. The present effort is to combine a wave model and a porous wave model for three-dimensional problems. A simple grid generation program is also developed to facilitate the numerical computation. The numerical model is first verified by the results of waves passing submerged impermeable structures. Then the model is used to study three-dimensional effects of submerged porous structures on passing waves. Wave profiles along the centerline of the structure in the wave field are used to compare with two-dimensional results. The results show that the present model can duplicate the cases of waves passing submerged impermeable structures. For the cases of submerged porous structures, the results show that in comparison with the two-dimensional problem there exist diffraction effects due to the submerged structures. Since the structures are submerged the incident waves are transmitted over the structure while waves are partially reflected. Due to the submerged structures the transmitted waves generate focusing behind the center of the structures. Three-dimensional wave patterns are presented, and characteristics of transmitted waves are also investigated.