A numerical study of the solidification process in a rectangular enclosure has been conducted for a binary mixture using three different wall cooling configurations. The simulations were run for unidirectional bottom and top cooling with the addition of sidewall cooling to demonstrate the effects of the chilled wall on macrosegregation in the forming solid. Solutions were obtained by solving the continuum conservation equations of mass, momentum, energy, and species for a hypoeutectic aluminum-copper alloy (Al-Cu). A nonuniform grid, based at the cold wall, was used for the calculations. Results show that different macrosegregation patterns are produced depending on wall cooling configuration. Bottom cooling simulations produced large pockets of Cu-rich fluid although the segregation was generally uniform throughout the mushy region. Double-diffusive cells were noted to occur in the case of top cooling, which increased the redistribution of species throughout the liquid pool. The addition of vertical wall cooling appreciably reduced the global segregation of species; however, locally severe segregation was reported in this case due to the effects of thermal and solutal buoyancy forces in the liquid region.
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