Numerical Study On Wave Dissipation Performance Of Permeable Caisson Breakwater

In order to make breakwater has good wave dissipation performance,shielding effect and water exchange ability,a new type of permeable breakwater was proposed in this paper.The influence factors of the wave dissipation performance of breakwater were studied by numerical simulation.The breakwater can be improved by combining with perforated caisson and the influence of perforated rate on transmission and reflection coefficients were analyzed.The main research contents and conclusions were as follows:Firstly,a 3-D numerical wave flume was established.By comparing with theoretical solution of regular wave and physical model test results,accuracy of the numerical flume in solving the problem of wave action on structures was verified.Based on the numerical wave flume,interaction between wave and permeable caisson breakwater was simulated.Results show that the breakwater mainly consume wave energy by resonance and breaking in channel.The relationship between transmission coefficient K_t and reflection coefficient K_r with F,c,W/L,L/d and H/d were analyzed under 110 conditions,and the empirical formulas were given.Resonance occurs in transmission channel at kh=1.25,and the maximum wave height in channel was about 3 times of the incident wave height.The structure was improved by panel perforated to improve the wave dissipation performance.When perforating rate of front panel was 25%,the reflection coefficient can be reduced by 20%~70%.When perforating rate of the front panel increased from 25%to 35%,the reflection coefficient increased but still less than that of the structure without opening.When front and inner panel were both perforated,results show that at perforating rate25%,K_t can be reduced by 50%~80%,and the resonance wave height in channel can be reduced by 15%~65%compared with the original structure.The resonance frequency moved to low frequency direction.When perforating rate of inner panel increased from 25%to 35%,K_t and resonance wave height were further reduced while K_r was increased.