Research And Optimization Of Fluid-solid Interaction Simulation Based On Non-spherical Particles

In this dissertation,the fluid-solid dynamics simulation method for arbitrary solid phase is studied.Based on the existing LBM-IMB-DEM coupling method,algorithm theories and simulation program design were improved and optimized to realize the liquid-solid two-phase coupling simulation for complex non-spherical particulate system,which consists of a large number of arbitrary shaped polygonal particles,static or moving walls,and complex porous media.The specific research contents of this dissertation are as follows:(1)Integrate and extend the LBM-IMB-DEM model.The "Convex Decomposition method" improved scheme for polygon DEM model was proposed to simulate arbitrary polygons.Additional algorithms were introduced for special cases such as penetration collision.The fluid dynamics simulation utilizes the LBM model and the BGK scheme.The boundary adaptation of polygonal solid phase was also performed for the IMB scheme.(2)A complete simulation program on the MATLAB~? platform was establish.A series of optimization algorithms including DEM time step testing method,sequential scanning algorithm and fast solid volume fraction computing algorithm were proposed,which greatly reduced the amount of computation.The overall calculation process was optimized by adopting programming schemes such as DEM Sub-cycle Method,bounding box and neighborhood list with bubble sort.(3)Three simulations,fluid pasting rectangular obstacles,particle free falling in the tube,and kinetic energy validation of DEM particles collision,were designed and performed.The fluid dynamics simulation module,fluid-solid coupling module,solid force and motion calculation module were verified in detail respectively.Through the above simulations,the applicability of the Convex Decomposition method to moving particles and complex walls is also confirmed.(4)Three representative chemical engineering processes(porous media airborne particles filtration,fluidized bed and rotating drum)were simulated.According to the actual needs of each simulation,the functions of the program were extended correspondingly.The extended program results are matched with the quantitative and qualitative characteristics of each scene to verify the application range of the program.The LBM-DEM method was studied and expanded from four aspects: algorithms,programming,verification and practice.Several algorithm improvement and optimization strategies are proposed.An integrated simulation program was built and verified.All these works enrich the non-spherical particulate system's theory and practices of simulation.