Applied Study Of Lattice Boltzmann Method For The Computational Fluid Dynamics

Fluid structure interaction (FSI) problem with moving boundaries is a hot topic in computational fluid dynamics (CFD). It’s critical to choose a numerical calculation method before carrying out a research of fluid dynamics. As an efficient mesoscopic numerical method in CFD, the lattice Boltzmann method (LBM) is applied for the FSI problem in this thesis.The present thesis covers three main parts:(1) The LBM is used for problems of flow past rotating cylinders and an elastic cylinder;(2) New grid refinement technology and curved boundary method are developed;(3) The immersed boundary method (IBM) is combined in the framework of LBM and applied for the problem of flow past an elastic cylinder.The first part introduces the theory of LBM. Several existing grid encryption technologies and curved boundary condition treatments are given. The grid refinement tecnology improves the accuracy and efficiency of the numerical calculation, and the curved boundary condition treatments exactly considers the curved edge’s shape. The problems of flow past rotating cylinders and an elastic cylinder is numerically studied. The dynamic characteristics of the cylidners and the structure of the flow are investigated in details.The second part presents the developments of the grid refinement technology and curved boundary treatment in LBM. In the new grid refinement technology different blocks communicate with each other by docking connection, the distribution functions of the common points on the boudanry are defined by the coarse and finer mesh block, then the interpolation process is avoided and thus the time required reduces. The new curved boundary condintion treatment unifies the interpolation step as well as the processing for static and moving boudanries.The third part investigates the immersed boundary method. The IBM has prominent advantages in dealing with the complex fluid-structure interaction boundaries. The problems of flow past an elastic cylinder is again studied with the IB-LBM. The numerical results manifest that the problem of local oscillation of the fluid force is solved with corrent IBM.