Transmitted and Reflected Coefficients for Horizontal or Vertical Plate Type Breakwater

Surface or submerged horizontal or vertical plate can be considered as a new concept breakwater. This paper investigates the wave-plate interaction of this type of breakwater by use of the boundary element method. The relationships of wave transmitted and reflected among plate thickness, submergence and length are carefully studied by numerical simulation. It is shown that： （1） The transmitted coefficients of submerged horizontal plate or vertical plate will become larger with the increase of plate thickness and reduce rapidly with the decrease of plate submergence. （2） Both surface horizontal and vertical plate are efficient for intermediate and short wave elimination, but vertical plate is more effective. （3） Submerged horizontal plate can act more effectively than submerged vertical plate does. With all wave frequencies, the vertical plate almost has no wave elimination effect.

Study on Scattering Wave Force of Horizontal and Vertical Plate Type Breakwaters

The interaction between wave and horizontal and vertical plates is investigated by the boundary element method, and the relations of wave exciting force with plate thickness, submergence and length are obtained. It is found that： 1） The efficient wave exciting force exists while plate submergence is less than 0.5 m, and the plate is very thin with order O（0.005 m）. 2） The maximum heave wave exciting force exists, and it is the main factor for surface and submerged horizontal plate while the roll force can be ignored. 3） The maximum sway wave exciting force exists, it is the main factor for surface or submerged vertical plate, and the roll force is about 20 times of horizontal plate.

Flow Field Analysis of Submerged Horizontal Plate Type Breakwater

Submerged horizontal plate can be considered as a new concept breakwater. In order to reveal the wave elimination mechanism of this type breakwater, boundary element method is utilized to investigate the velocity field around plate carefully. The flow field analysis shows that the interaction between incident wave and reverse flow caused by submerged plate will lead to the formation of wave elimination area around both sides of the plate. The velocity magnitude of flow field has been reduced and this is the main reason of wave elimination.

Numerical Simulation of the Hydrodynamic Characteristics of the Porous I-type Composite Breakwater

Based on the three-dimensional Reynolds-averaged Navier-Stokes equation with the closure of renormalization group k-εturbulence model and volume of fluid method,a wave-breakwater interaction numerical flume was developed to examine the wave-structure interaction of the porous I-type composite(PITC)breakwater.The transmission and reflection coefficients of the breakwater at different wave steepness H/L are quantitatively analyzed,and the wave-dissipating performance of the breakwater is compared.By changing the submerged depth of the breakwater,the velocity field,and vorticity field in the wave propagation process are analyzed,and the optimal working water depth of the new breakwater is explored.The results show that the vertical wave force on the PITC breakwater is greater than the horizontal wave force.In addition,during the wave dissipation process,the transverse baffle provided by the new breakwater destroys the trajectory of the water particle.In the interior of the wave-breaking chamber,the water that enters from the gap of the permeable plate mixes with the water entering through the bottom hole.The turbulence created by this process further dissipates the wave energy.The relative submergence depth of h/d has a great influence on the hydrodynamic characteristics.When the relative depth is large,most of the wave energy enters the breakwater,the wave energy dissipation of the breakwater is large,and the wave-absorbing effect is good.These research results provide important referential data for the study of permeable plate breakwaters.