Wave damping characteristics of deeply submerged breakwaters

A study on the improvement for the problem of wave transmission in deeply submerged breakwater is carried out in this paper. In the theoretical analysis the complex eigenfunction approach is employed. In this study the submerged breakwater is assumed to be a rectangular form and vertically stratified with multislice porous material. Theoretical computations are performed for both single-slice (nonstratified) and multislice submerged breakwaters. Half of the water depth is selected as the submergence of the breakwater. The computational results show that, for a single-slice breakwater, the transmission coefficient could be effectively reduced, while the porosity of structure material is as high as 0.8 and the thickness-depth ratio b/h = 20 (b is the structure thickness, and h is the water depth). A large transmission coefficient can be predicted for a deeply submerged breakwater without sufficient thickness-depth ratio. However, this problem could be improved by adopting a multislice structure concept in which the breakwater structures with more slices are more effective in reducing the transmission coefficient.