Study On The Dynamic Responding Characteristics And Wave Elimination Effect Of Floating Breaker Under The Influence Of Island Reef Topography

The floating breakwater is an important marine structure used to attenuate the incident waves from the open sea in the port.Waves propagate from deep water to near-island reef waters.Due to the influence of topography,the characteristics of waves are very different from those of deep water.Water particles and its motions will be disturbed by the floating body and topography.Breakwaters will has strong nonlinear coupling motion under complex environmental conditions.Currently,some commercial softwares,such as AQWA and SESAM etc,can simulate the effect of simple topography on the hydrodynamic performance of moored flaoting structures.However,it cannot simulate the motion of viscous liquid caused by the changes of topographic changes.Moreover,the dynamic mooring line is not taken into consideration.Therefore,the evolution of waves cannot be obtained.In this paper,a smooth particle hydrodynamics method(SPH)is used to establish a numerical method for the coupled hydrodynamic analysis of floating breakwaters with mooring systems based on the catenary equations.The dynamic response,mooring force and wave attenuating coefficient of floating breakwaters are measured by experiments.The experimental results are compared with the numerical results.The numerical method has a sufficient accuracy.On this basis,the motion response and wave attenuating mechanism of floating breakwaters with different islands and reefs are studied.The main contents of this article are showed as follows:1.The SPH method was used to code the wave modeling program to establish a two-dimensional wave flume.Based on the linear wave attenuation theory,the velocity and pressure gradient of the particles in the wave-absorbing layer were artificially attenuated,and the sponge layer was established to attenuate the wave reflection.Based on catenary equations and fluid-solid coupling theory,a numerical method for floating breakwater with mooring system under wave action is established,and the coupled numerical solution of wave and floating body is achieved.2.Based on the coupled hydrodynamic analysis method of floating breakwater with mooring system established in the previous section,the wave-absorbing effect and dynamic response characteristics of floating breakwater with the islands and reefs are considered.This paper mainly analyzes the influence of the depth and size of the reefs,location,slope of the reefs and other factors on the wave attenuating performance of the breakwater,and the wave attenuating performance and the motion response of the floating breakwater with multi-reefs.3.The experiment is carried out.The motion responses,mooring force and wave attenuating coefficient of floating breakwater are measured and compared with the numerical results.The results show that the numerical method has a sufficient accuracy.