The Study Of Hydrodynamic Characteristics Of Focusing Wave Propagating Over A Typical Reef Island

For China,the South China Sea has not only important resource value,but also important political and military value because there are numerous reef islands in the South China Sea,which,if properly developed and utilized,will greatly facilitate China's exercise of sovereignty over the South China Sea.However,most of the reef islands are far away from the mainland with unique topographic and geomorphic features,the hydrodynamic characteristics near the reef area are more complex than the general coast,which requires a lot of experiments and numerical investigation.For island construction projects,relevant studies on the hydrodynamic characteristics of waves are of great significance.But there are few studies on the hydrodynamic characteristics of extreme waves on reef islands for the present.In this paper,the idealized island topography was used to carry out the reef island physical experiment under the condition of deep water in the water tank.By focusing the wave train generated by the wave generator on the island slope,a wave with extremely high wave height was generated.In this way,the extreme waves in the reef area under real conditions can be simulated.The experiment considers two typical reef topography,one is conventional reef topography without reef crest,and the other is reef topography with reef crest and lagoon.Different wave parameters were considered in the selection of wave groups,and 40 cases were determined.During the experiment,different acquisition systems were used to measure the free surface and velocity changes in the upper part of the reef topography,as well as the wave pressure and climb at the straight wall at the end of the topography.After that,the experimental results were classified and analyzed,and the effects of different focusing amplitudes,component spectra,and frequency of component waves on the propagation of focused waves in the reef area were discussed,and the relevant physical laws were summarized.In order to further study the characteristics of extreme wave propagation near the reef topography,a Non-hydrostatic mathematical model was used to stimulate the physical experiments.The applicability of the numerical model is verified by physical model experiment results,and the reliability of the numerical model is confirmed.Then,a series of numerical calculation results were used to supplement the insufficient data of the physical model experiment,so as to further study the propagation characteristics and rules of the focused wave on the reef terrain.