Modified cellular automaton model for the prediction of dendritic growth with melt convection.

Abstract

A modified cellular automaton (MCA) coupled with a momentum and species transport model has been developed in order to predict the evolution of dendritic morphology during solidification of alloys in the presence of melt convection. In the present model, the cellular automaton algorithm for dendritic growth is incorporated with the transport model, for calculating fluid flow and mass transfer by both convention and diffusion. The MCA model takes into account the effects of the constitutional undercooling and the curvature undercooling on the equilibrium interface temperature. It also considers the preferred growth orientation of crystals and solute redistribution during solidification. In the transport model, which is coupled with cellular automaton approach, the SIMPLE scheme is employed to solve the governing equations of momentum and species transfers. The present model was applied to model solutal dendritic growth of an Al-3mass%Cu alloy in a forced flow. The simulations reproduced the typical asymmetric growth features of convective dendrites with various preferred orientations. The effects of inlet flow velocity on the solute redistribution and the growth velocity of a dendritic tip were quantitatively investigated.