Numerical Analysis Of Fluid-Structure Interaction Between Large Sloshing Viscous Fluid And Tank

Large-scale liquid-filled tanks are widely used in the oil industry, and their failure resulted in earthquake may lead to many serious seismic disasters. Researches on this problem have been carried out in many countries over the past decades. Although some results have been achieved, there are still many problems unsolved. Considered the complexity of both theoretical models and experimental methods of the problem, a finite element model is developed in this dissertation. The numerical study has been made on these liquid-filled tanks as a fluid-structure interaction system consisted of large-scale thin-walled structures and viscous fluid with large sloshing.For the large-sloshing problem of viscous fluid, a finite element method called direction method is developed by ALE (Arbitraty Lagrangian Eulerian) description and fractional method. ALE can easily capture the free surface of liquid and the fractional method can allow the equal-order interpolation for the pressure and velocity. By comparison with the traditional method (intermediate velocity method), direction method has some advantages: One is that it derives the pressure equation directly from the equation of motion, but the intermediate velocity method employs the intermediate velocity to derive the pressure Poisson equation and some errors would be introduced with the intermediate velocity. The other is that direction method is more efficient than the intermediate velocity method.In ALE formulation the fluid-structure interaction analysis becomes a three-field coupling problem of the fluid field,the solid field and the fluid dynamic mesh. Based on the characteristics of the coupling interface between fluid and solid a staggered solution procedure is developed. This method divides the coupling into two parts, one is fluid field and the other is solid field, and the two parts are calculated in turn and staggeringly in the numerical integration.A finite element code for the analysis of fluid large sloshing with free surface has been developed on the bases of the theories and methods discussed in this thesis, and combined with ABAQUS program by some user subroutines of ABAQUS according to the scheme of the staggered procedure. The combined program can be used to the viscous-elastic-plastic structure interaction problems, especially to some more complex fluid-structure interaction problems because of the strong ability of nonlinear analysis and various types of finite elements of ABAQUS.Several examples have been given by the above program. Those examples include three-dimensional fluid large sloshing with different viscous coefficients, the dynamic response of the liquid storage tanks under the seismic excitations. The results show the applicability and reliability of the above theories, numerical methods and the program for the fluid-structure interaction.