Wave damping characteristics of deeply submerged breakwaters

A study on the improvement for the problem of wave transmission in deeply s ubmerged breakwater is carried out in this paper. In the theoretical analys is the complex eigenfunction approach is employed. In this study the submer ged breakwater is assumed to be a rectangular form and vertically stratifie d with multislice porous material. Theoretical computations are performed f or both single-slice (nonstratified) and multislice submerged breakwaters. Half of the water depth is selected as the submergence of the breakwater. T he computational results show that, for a single-slice breakwater, the tran smission coefficient could be effectively reduced, while the porosity of st ructure 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 transmissi on coefficient can be predicted for a deeply submerged breakwater without s ufficient 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 coefficie nt.