Cast filling simulations of thin-walled cavities Original Research Article

Computer simulation models of casting processes which couple the velocity potential approach with a transient Bernoulli equation are developed. Instead of employing three primitive variables, displacement, velocity and pressure, only one variable-velocity potential is needed. When the thickness integrated equation is also employed, the method can provide practical results with very reasonable computing time and storage for the 3-D casting of an arbitrary shape thin-walled cavity. In this study, the flexibility of the finite element method in dealing with complex geometries and the efficient algorithm of volume of fluid (VOF) approach for tracking moving free surfaces are combined for solving casting filling problems. Multiple free surface contacts are developed when the stream finally turns back and impacts the original free surface. A double-node scheme is developed to treat these multiple free surface contacts. The movement of the interface is small and an inflexible wall across the separating surface is assumed. Because the casting process involves phase change, and the interface between the solid and liquid is generally an unknown curve, the enthalpy model with fixed mesh is used to determine the temperature distribution and the thickness of the filling. Numerical examples for prediction of filling patterns, effects of solidification on patterns and parametric studies are presented. Fairly good agreement between this method and experimental results and other numerical simulations have also been obtained. The computational techniques developed in this study can provide a powerful and flexible tool for analyzing the fluid flow and heat transfer in metal casting of thin-walled cavities and can help design engineers reduce the costly and time-consuming process of designing complex molds for the manufacture of casted parts.