THE INTERFERENCE OF A SEMI-SUBMERGED OBSTACLE ON THE POROUS BREAKWATER

The interaction of a linear water wave in a channel of constant depth impinging on a vertical thin porous breakwater with a semi-submerged. and fixed rectangular obstacle in front of it is investigated. The wat er follows conventional assumptions as an irrotational, incompressible , and inviscid fluid flow. The solid skeleton of the porous breakwater is assumed to be rigid and thin. We get the general solution by apply ing the eigenfunction expansion method and solve it with a numerical m atrix solver. In order to verify the correctness of the general soluti on, wave flume experiments are conducted. Two asymptotic solutions for long and short incoming waves are also obtained. Both experiments and asymptotic solutions show good agreement with the general solution at proper limits. Finally, the effect of the fixed obstacle on the porou s breakwater is discussed, and a general guide of how to obtain better energy trapping is delivered. (C) 1998 Elsevier Science Limited. All rights reserved.