Modeling of the Equiaxed Dendrite Coarsening Based on the Interdendritic Liquid Permeability during Alloy Solidification

In this investigation, a model has been developed for determination of liquid flow permeability through dendritic structures during equiaxed dendrite growth. Two separate computational models have been coupled for modeling the permeability and coarsening in mushy alloys. The dendrite growth has been simulated using a cellular automation finite difference analysis, while the fluid flow has been modeled employing computational fluid dynamic. A new approach has also been proposed in calculation of the coarsening phenomenon as well as modification of the micro fluid flow based on switching between permeability and pressure gradients at high solid fractions. The predictions show that in high solid fractions, an iterated algorithm on the permeability gradient at a given pressure is closer to the experimental results. Therefore, under these circumstances, the continuity equation would not be satisfied by prediction and correction of the pressure field. Instead, the continuity equation would be satisfied by iteration and correction of the local permeability at a constant pressure gradient.