Research On Computation Method Of Moving Structure In Fluid Field And Its Application

In the past decades, with the global environmental degradation, El Nino phenomenon has been inducing the lasting rise of sea level. The bridges in coastal regions are exposed in the extreme complex dynamic environment, including wind, tide, wave, ocean-current, etc. When typhoon or hurricane passes, the effect of surge makes infrastructure failure. Especially for bridges with small and medium span, they suffer great losses because of insufficient underneath clearance. The failure and losses could be attributed to undeveloped cognition research on fluid flow effect. Hence, the coupling issue between fluid flow and structure is turning to be a hot topic.The source of topic of the thesis is a project funded by the National Natural Science Foundation of China, research on damage form and mechanism of offshore bridges caused by the extreme wave loads. It develops a locating approach of interface suitable for all kinds of2-D motion of rigid body. In addition, the numerical computation of bridge deck subjected to linear wave is discussed. The numerical model based on the fixed Cartesian grid system is further ameliorated. The combination of updated shape coefficient treatment and amended locally relative stationary is employed to compute moving structure in fluid field. At last, numerical tests of couplings of fluid and structure under various situations are conducted, which shows promising scientific research value and application prospect. The solution of Reynolds Average N-S Equation, the flow field governing equation, employs two-step projection method in scheme of finite difference. Furthermore, the treatment of border cells is another critical process. Volume of Fluid is employed to define free surface, and partial-cell treatment to track interface.In order to verify new algorithm and check model appliance, it conducts some numerical tests and the computing results is analyzed here. It shows that simulations of rectangle column oscillation within s narrow range in steady flow and courses of general motion of a rigid body with complex configuration in fluid field are rational. At last, model computes the load history of π section bridge deck in different hydraulic conditions and wave propagation. In addition, author summaries the cause of structure failure and suggests some preliminary control measures.