Wave damping characteristics of deeply submerged breakwaters

A study on the improvement for the problem of wave transmission in deeply submerged break-water 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.