In this present study, we made a first attempt to investigate physical transformations of incident waves in surf and swash zone and hydrodynamic phenomena of detached and submerged breakwaters. For an accurate simulation of the complicated wave deformation, Three-Dimensional numerical model with Large Eddy Simulation has been developed recently and expanded properly for the current applications, which is able to simulate an accurate and direct WAve· Structure· Seabed interaction (hereafter, LES-WASS-3D). LES-WASS-3D has been validated through the comparison with experimental results for limited cases, and has been used for the simulation of wave run-up in sandy beach, mean fluid flows over and around submerged structures and swash zone (alongshore/rip current), and spatial distribution of wave height in wide fluid regions. In addition, a strategy of efficient deployment of the submerged breakwaters has been discussed.
Profound understandings of the 3-D beach processing in the coastal regions require fundamental studies for hydrodynamic characteristics of wave transformations in swash zone and assessments of the run-up heights (Ruggiero et al., 2001; Sallenger, 2000). Many other relevant studies can be found in many references (Patrick J. Lynett, etc., 2002). The frequent disappearance of beaches has great impact in the environment of the costal region, in tourism and economy of regions affected by this aggravation of beach erosion. Thus, recently, submerged breakwaters become an alternative solution in many countries (such as Korea, Italy, Japan, Spain, Portugal etc.) and in the view of a wide variety of armored structures to coping with this problem and with reduced environmental impacts (water circulation) and favorable scenic views. The gradually growing installation of the detached and submerged breakwater (in places where tidal variations are small) increases the complexity of the wave interaction mechanism between surf zone and structural zone hydrodynamics.
