Numerical Simulation Method And Application Of Fluid-coastal Structure Coupling System

China has a very long coastline.In coastal areas there are a large number of fixed structures and floating installations,which are influenced by the waves and the surrounding fluids.It is of great significance to study the dynamic coupling effect between fluid and coastal structure.The results of these studies can offer references to design and improve the coastal structure and device.With the improvement of computer technology and computing methods,more and more large-scale engineering problems are solved using numerical simulation methods.The simulation method can provide a more accurate result,improve the computation efficiency and save the cost of experiments.The paper mainly studies the fluid-structure coupling system using numerical simulation methods on a high performance computing platform.We propose the numerical simulation method for coupling system between the coastal structure and fluid,and apply it to the specific engineering problems.The main research contents include:Numerical modeling methods for fluid-coastal structure coupling system are presented.The fluids such as water and air are modeled with the ALE formulation and the structure area is modeled with the Lagrangian formulation.The multi-material ALE element is used to solve the problem that the fluid unit may consist of two different substances.To simulate the dynamic coupling between fluid and structure effectively,the penalty function method is used to model the transmission of variables on the interface of the coupling system.The contact relation between different parts is also processed using the penalty function method.High performance computing methods for fluid-coastal structure coupling system are proposed.The numerical simulation of a large nonlinear fluid-structure coupling model needs a great amount of calculation,and needs considering thes fluid-solid coupling interface and dynamic contact interface.The existing parallel computing partition method is mainly used to obtain partitions with each partition having the same amount of nodes and elements,but it cannot guarantee a balanced distribution of calculation for the coupling in each partition domain and causes a decline in the parallel computation efficiency.Hence on the Drawing 5000 A high performance computing platform of Shanghai Supercomputer Center,load balancing coordinate bisection method is designed.To verify the feasibility of the partition method and its parallel efficiency,engineering applications of two coupled systems,the fluid-coastal breakwater and fluid-coastal gasbag-type floating bridge,are further investigated and analyzed.Numerical simulations of the fluid-breakwater coupling system are carried out.The numerical wave flume is constructed,and different waves such as regular waves,irregular waves and solitary waves are generated based on the wave generation principle.Wave overtopping on the breakwater is modeled and the effects of the width of levee crest and the elevation of wave wall on the overtopping are further analyzed.The process of wave impacting on the breakwater is simulated.The distribution of maximum wave pressure on the front faced wall is analyzed as well as the deformation and stress response of the wave wall.A scaled physical model of the breakwater is designed and constructed and then tests of the wave overtopping and impacting are conducted.The numerical simulation results are compared with the experiment results.The vehicle collision on the posterior wave wall under the action of waves is simulated,and the factors such as load capacity and the impact distance affecting the impact force and the principle stress of the posterior wall is evaluated.In the end,a hybrid modeling method is proposed and a three dimensional finite element model of breakwater is constructed.The stress conditions at the critical section of the breakwater are analyzed.Numerical simulations of the fluid-gasbag type floating bridge coupling system are carried out.Appropriate meshes are generated and a three dimensional finite element model of the floating bridge is modeled.By comparing to the results of a scaled physical test,the numerical simulation method is effectively validated.To prevent from the resonance of the floating bridge,modal analysis of the floating bridge is firstly performed and the effect of different joint connections on the natural frequencies is investigated.The vehicle driving on the floating bridge is modeled.The effects of load capacity,the speed of the vehicle and its acceleration on the dynamic response of floating bridge are studied.Deformation and stress conditions of the floating bridge gasbags are analyzed.The effects of the assembly clearance and the inflation pressure are also investigated.The impact of wave on the floating bridge is modeled and the effects of wave height and incident angle on the dynamic response of floating bridge are further analyzed.