Adaptive refinement techniques based on tetrahedral and hexahedral grids for finite element analysis of mold filling in casting processes

A 3-D finite element model combined with a volume tracking method is presented in this work to simulate the mold filling for casting processes. Especially, the analysis involves an adaptive grid method that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Adaptive grid based on VOF method is developed in tetrahedral and hexahedral elements. Through a 3-D analysis of the benchmark test of the casting process using two types of elements, the efficiency of the proposed adaptive grid method is verified.