WAVE INTERACTION WITH SEMIPOROUS CYLINDRICAL BREAKWATER

The results of a theoretical investigation into the interaction of linear water waves with a cylindrical breakwater surrounding a rigid vertical circular cylinder are reported. The breakwater itself consists of a bottom-mounted, surface-piercing cylindrical structure that is porous in the vicinity of the free surface and becomes impermeable at some distance below the water surface. Under the assumptions of linearized potential flow, the coupled problem of flow in the interior and exterior fluid regions is solved by an eigenfunction-expansion approach. Analytical expressions are obtained for the wave motion in both the interior and exterior flow regions. Numerical results are presented that illustrate the effects of the various wave and structural parameters on the hydrodynamic loads and interior and exterior wave fields. For certain parameter combinations, the semiporous, cylindrical breakwater may significantly reduce the wave field and the hydrodynamic forces experienced by the interior structure.