In the present study, the reflection performances of wave-trapping structure which comprised by two horizontal plates considering thickness and vertical walls was investigated numerically. It is expected to reduce the wave reflection in a certain extent by changing the dimension, shapes and configurations of this structure. Various numerical simulations were performed using the mass source wave- maker applied to the RANS equation model in a CFD code. Numerical results are obtained with the use of the wave model for regular waves, revealing the effects of the space between plates and wall, the plates length, the plates thickness, the submerged depth, the gap between two plates, the shapes and configurations of plates on the wave reflection characteristics. The results of numerical study show that a perfect structure size and configuration exists for the reflection coefficient reaches minimum. The results of this study, which is helpful for the application of double plate breakwater structure, will lay a foundation for the further study of the composite structure related to the double plates.
Conventional submerged breakwater can reduce coastal beach erosion, but it has the disadvantage of rapidly changing its neighboring wave field, due to excessive wave reflection. The submerged plate can overcome such disadvantage, and the vertical wave force acting on the wall was decreased and became balance. The horizontal plate can modulate wave energy changes smoothly, many researchers studied hydrodynamic performance of horizontal plates with amounts of wave energy passing through.
Patarapanich and Cheong (1992) studied the reflection and transmission characteristic of a horizontal double-plate system consisting of a seaward surface plate and a submerged leeward plate, and derived the reflection and transmission coefficients. Based on the linear potential wave theory, Usha and Gayathri (2005) investigated wave reflection and transmission over a horizontal twin-plate structure analytically, the twin-plate system consists of a horizontal single surface plate and a horizontal submerged plate of same dimensions just below the surface plate. The wave reflection and transmission characteristics on twin plate barriers were investigated experimentally by Neelaman and Gayathri (2006).