THERMOSOLUTAL FLOW IN METALS AND IMPLICATIONS FOR DC CASTING

摘要

A multicellular thermosolutal natural convection flow is observed in finite-volume numerical simulations of direct chill (DC) casting of binary Al-5.25wt%Cu alloy round billets. To further investigate and to be able to better understand the flow structures in the metal, i.e. a low-Prandtl-number liquid, a simplified problem of transient thermosolutal natural convection in an enclosure at relevant Prandtl, Schmidt, and Rayleigh numbers is studied first. The evolving flow is described and possible parallels between thermosolutal flows in high- and low-Prandtl-number fluids are drawn. Then, computed flows in the DC cast billets are presented and explanations of the impact of variations of casting temperature and casting velocity on the flow structure are proposed.