Numerical Modeling of Solidification Process Using the Enthalpy-Porosity Technique

The enthalpy-porosity technique is used in this study for numerical modeling of solidification of water and binary mixture of ammonium chloride and water (NH₄Cl-H₂O). A two-dimensional geometry was used to simulate the solidification process in the rectangular and trapezoidal cavities. The liquid fraction is computed based on an enthalpy balance. The mushy zone is modeled as pseudo-porous medium in which the porosity decreases from 1 (liquid) to 0 (solid) as the material solidifies. The solidification with single side cooled wall as well as both cooled side walls was investigated. The frozen layer thickness, the convective flow patterns, and the temperature distribution were obtained. The results obtained in the course of the study showed that the shape of the solid region and the convection pattern in the melt region compare well with experimental data obtained by Particle Image Velocimetry technique. The enthalpy-porosity model is predicting well the flow pattern and the thickness of the frozen layer.