An Improved Columnar Solidification Model Coupled With Anisotropic Mush Permeability

To get a basic understanding of the solute transportation and chemical inhomogeneity in directional columnar structures, the anisotropic permeability law was integrated into a volume-averaged columnar solidification model. Ten isotropic and anisotropic permeability laws were adopted to discuss the effect of the mushy zone permeability on macrosegregation and channel segregation in a benchmark solidification problem. Results showed that the permeability coefficient had obvious effects on the global macrosegregation and the morphology and severity of channel segregation. An uneven solute distribution resembling the columnar morphology was observed. Anisotropic permeability laws predicted distinct and physically justified segregated channels because the effect of directional columnar structures on the solute transportation could be considered. The volume-averaged solidification model was verified by a grid sensitivity analysis. Calculating channel segregation was more sensitive to the mesh size than the macrosegregation. These findings preliminarily illustrated the importance of considering the anisotropy nature of columnar structures in numerical studies of channel segregation.

Automated summary

In order to understand solute transportation and chemical inhomogeneity in directional columnar structures, anisotropic permeability law was incorporated into a volume-averaged columnar solidification model. Ten different permeability laws were used to investigate the impact of mushy zone permeability on macrosegregation and channel segregation in solidification. The results showed that permeability coefficient had significant effects on macrosegregation and channel segregation, with an uneven solute distribution resembling the columnar morphology. Anisotropic permeability laws predicted distinct and physically justified segregated channels, considering the effect of directional columnar structures on solute transportation.