A MIXTURE TWO-PHASE MODEL FOR PREDICTING MACROSEGREGATIONS DURING SOLIDIFICATION

摘要

The formation of macrosegregations during solidification is caused by the relative motion between melt and growing solid. Recently, Eulerian multiphase approaches came up to describe this relative motion. Because conservation equations must be solved for each considered phase, the Eulerian approaches have high computation costs. In order to reduce these costs, a mixture model is suggested in this paper. For the mixture phase only one single momentum and enthalpy equation has to be solved. A so-called drift flux model handles the relative motion between the liquid and the solid. In addition, mass and species conservation are solved for each phase. Grain nucleation and transport is considered with a suitable number density conservation equation. It turned out, that the major features of an Eulerian approach remains, but the calculation costs are reduced and the solution procedure is more stable. The model is applied for the solidification of a cylindrical steel ingot casting. The results indicate that the mixture model can be practically used to simulate large ingot casting at industry scale by making full use of the advantages of the CFD technology in terms of sophisticated solidification modeling details.