Melt flow and macrosegregation in DC casting of binary aluminum alloys

Macrosegregation in a DC casting of an Al-4.5%Cu billet is modeled using the one-phase continuum mixture model, solved by the finite volume method. Results of macrosegregation computations show a complex multicellular thermosolutal flow. This indicates the need for an accurate numerical solution of the flow field. An investigation of mesh convergence of the flow field solution, using first-order upwind and ULTRA-QUICK convection discretization schemes, shows a transition of the flow structure increased numerical accuracy. It is concluded that accurate higher-order numerical methods are essential for flow modeling in simulation of macrosegregation.