Accurate Mold Filling Simulation using Cut Cell in the Cartesian Grid System

Abstract

In the field of casting flow analysis, despite good quality analysis results it is difficult to apply body-fitted grid. This is on account of difficulties in grid generation and efficiency. Cartesian grid based numerical techniques for casting flow have been developed to address this issue. However, the Cartesian grid cannot be used to accurately represent complex shapes with many sloped and curved surfaces. A step grid that does not match the precise geometry leads to unsound results in flow analysis, such as loss of momentum during flow and false filling pattern. In this study, a Cut Cell method based on Partial Cell Treatment is applied to the casting flow analysis in the Cartesian grid system. The newly developed numerical method is then verified in comparison with water model experiments and practical casting experiments. The conventional and Cut Cell methods of using the Cartesian grid are also compared. The numerical results of the two methods are compared according to the number of grids, and it is confirmed that the increased number of grids cannot solve the disadvantages of the Cartesian grid. In addition, the practical castings are analyzed for each casting process. It is confirmed that the numerical error in the conventional method can be rectified by the Cut Cell method. Finally, the computational time of the conventional method and the Cut Cell method are compared. In conclusion, it is confirmed more accurate Cartesian grid based casting flow analysis is possible by using Cut Cell method without Body-Fitted Coordinate. However the Cut Cell method involves a long calculation time. There may be no significant difference between the two methods depending on the shape of castings or the casting process. Therefore, in the analysis of casting flow, it is necessary to selectively use the conventional Cartesian grid method or the Cut Cell method considering the accuracy and efficiency of analysis.