Numerical Simulation Of Flow And Heat Transfer Using Smoothed Particle Hydrodynamics

Accompanied by the introduction of numerical simulation, the research of castingprocess has got rid of the dependence on traditional trial-and-error method. Numericalsimulation plays an important role in the prediction of casting defects, such as gas porosity,oxide inclusion, cold shut and misrun. Numerical simulation has become an effective methodin optimizing mould design, guaranteeing casting quality, modifying casting process. Basedon whether the computational domain needs meshing, numerical methods could be dividedinto grid-based numerical method and meshless method. Due to the difficult in fittingcomplex curves and surfaces and the shortage of accuracy in computing free surface ofgrid-based method, meshless methods, especially the Smoothed Particle Hydrodynamics,have been revealing its prosperity in dealing with the violent free surface flow in the processsimilar with casting process.Based on the basic theory of computational fluid dynamics and SPH, the SPH forms ofgoverning equations have been derived, and the implementation and application of SPH incasting process have been studied. Based on repulsive force model and ghost particle model,the treatment of solid wall has been established. The treatments of inlet boundary and circularboundary have also been realized. In view of the linked-list method, a new method namedrefined linked-list method has been used as the searching method for the detection ofneighboring particles. A WCSPH calculation program focused on mould filling process incasting process has been established. Through the comparison of WCSPH results with FiniteDifference Method and benchmark test results, the effectiveness of WCSPH in mould fillingprocess simulation has been validated. By the introduction of MLS correction method, theaccuracy in inconsistency problem has been strengthened. Water filling experiment isestablished to verify the established WCSPH program’s ability in dealing with mould fillingprocess, in which the viscosity is handled by adding polyacrylamide. To validate theeffectiveness of ghost particle model used in boundary condition treatment, the dam breakingprocess is studied, especially the distribution of pressure and flow state.Because of the introduction of artificial compressibility and making the variation of density under certain control in traditional SPH, the incompressible fluid flow isapproximated as weakly compressible fluid flow. The application of incompressible SPH isstudied in the simulation of free surface flow. A model specified for free surface flow has beenestablished, a corresponding ISPH program has been developed to simulate violent freesurface flow, such as water impact phenomenon. Compared with weakly compressible SPH,ISPH is a semi-implicit method. The pressure is calculated by the solution of Poisson equationusing iterative method, and the velocity is computed by explicit method. By means of thestudy of impact of water columns, the effectiveness of ISPH in simulating free surface flowhas been validated.The SPH discrete form of Heat transfer equation is derived, which has been proved bycomparing the analytic solution with numerical solution in dealing with one-dimensional case.As the variation of temperature would exert an influence on the physical property of liquidmetal, a treatment of the temperature effect on physical property is introduced and a flow-heatcoupling program is established. A circular part is calculated to show the capability of SPH.To investigate the effect of latent heat, a temperature recovery method is included into thesolidification simulation. The cooling process of a T-shaped part is calculated by SPH andFinite Element Method (FEM) software MSC. Marc to study the temperature distributionrespectively, the accuracy of SPH heat transfer model has been verified.