Numerical Study Of Solitary Wave Transformation Over Fringing Reefs And Interaction With Vertical Seawalls Under The Influence Of Wind

Coral reefs are important land resources in China and are widely distributed in the South China Sea,East China Sea and other regions.Relying on the strategy of strengthening the country by the ocean,our country is vigorously developing coral reef projects.Solitary waves are extremely destructive ocean extreme waves,posing a serious threat to the construction of coral reefs engineering.Due to the existence of near-reef wind areas,the propagation and energy mechanism of solitary waves on the coral reef will change.Therefore,the research on the water power of solitary waves on coral reefs under the influence of wind and its interaction with buildings is of great significance for the construction of coral reefs.Based on the two-phase flow solver in OpenFOAM,this paper establishes a two-dimensional wind-wave hydrodynamic numerical model by using the relaxation zone wave-making method,and the reliability and accuracy of the model are verified by comparing the experimental data.Then,by setting different wind speeds,the effect of wind on the propagation of solitary waves on the coral reef terrain and their interaction with the vertical breakwater was studied.The variation law of wind speed,and the variation mechanism of wave load and waves overtopping discharge on vertical breakwater under different reef edge distances,different freeboard heights,and different breakwater widths with wind speed.Finally,based on the above research data and previous theoretical results,a prediction formula for the volume of solitary waves crossing the vertical breakwater on the reef flat is proposed considering the wind influence factor.The research results show that the effect of wind will accelerate the propagation of the solitary wave and make the solitary wave break up in advance.Under the influence of wind speed Uw=4,the wave surface was raised by 8.0%～31.1%.The existence of the wind increases the turbulent intensity of the solitary wave breaking,and makes the turbulent kinetic energy value of the breaking wave.and turbulence ratio dissipation rate value increases with the increase of wind speed.When there is wind,the kinetic energy and potential energy of the water body are significantly higher than those when there is no wind,and the increase in peak kinetic energy is 3.8%to 39.2%,and the increase in peak potential energy is 2.9%to 19.4%.The effect of wind is enhanced the reflection and transmission of the solitary wave on the front slope of the reef are improved.The wind will strengthen the vortex motion when the solitary wave and the vertical breakwater act.The impact force coefficient at low wind speed(Uw=1)has little change or even a decreasing trend compared with that without wind,and the impact force coefficient under high wind speed(Uw=3,Uw=4)is compared with that without wind.The overtopping pressure per unit area of the top of the breakwater increases with the increase of wind speed.When there is wind,the wave crossing process starts earlier and lasts longer than when there is no wind.The dimensionless single-width waves overtopping discharge increases with the increase of wind speed.When the wind speed is Uw=4,the dimensionless single-width waves overtopping discharge is about 1.31～6.13 times when there is no wind.This study will provide a theoretical reference for the design of protective engineering on coral reefs.