Two-phase flow modeling of air entrapment in high pressure die casting considering air compressibility and surface tension

Air entrapment is a serious defect in HPDC (high pressure die casting) process. In this paper a two-phase flow numerical model aimed at predicting this defect is developed. Two important physical factors are firstly considered in the modeling of HPDC process, namely air compressibility and surface tension. An ESOLA (Extended SOLA) algorithm is derived to solve the Navier–Stokes equation of compressible air. An interface capturing approach VOSET (coupled volume of fluid and level set) using geometric operation for level set function is adopted for capturing the melt/air interface evolvement and calculation of surface tension. The proposed model allows calculations with non-orthogonal mesh. The capability of the model is verified by comparing simulation results with analytical and experimental results.