FRONT TRACKING METHOD ON A FIXED GRID VERSUS ENTHALPY APPROACH IN MODELLING OF BINARY ALLOY SOLIDIFICATION

摘要

A novel front tracking technique on a fixed Cartesian grid, based on the kinetics of dendritic growth, is discussed. It is used to predict the influence of both alloy composition and convective heat transfer coefficient on the size of the undercooled liquid zone in front of columnar dendrite tips during solidification of Al-Cu alloys driven by conduction in a square mould. The model is compared with the enthalpy approach showing its superiority in the detection of the undercooled zone and, thus, in potentially modelling of columnar/equiaxed grain structures. The effect of natural thermal convection on the shape of the mushy zone is demonstrated by use of the enthalpy-porous medium model, and an approach to incorporating convection into the non-equilibrium front-tracking model is outlined.