Modeling of 3-D turbulent transport phenomena and solidification of a direct chill caster fitted with a metallic-foam-plated combo bag

The 3-D numerically simulated steady state results of an industrial size vertical Direct Chill (DC) slab caster fitted with a metallic-foam-plated combo bag melt distributor for AA-1050 aluminum alloy are reported. The turbulence in the melt and the mushy region solidification of the alloy are modeled through the popular low Reynolds number κ-ε model of Launder and Sharma and the enthalpy-porosity scheme, respectively. The transport of melt through the foam is modeled using the Brinkman-Forchheimer extended Darcy equation. The verification of the numerical model is performed by comparing the predicted and measured solidification front for AA-3104 rolling ingot reported in the literature. The inlet melt superheat and the porosity of the metallic foam of the combo-bag were kept fixed at 32 °C and 0.9, respectively. Parametric studies are carried out by varying two important parameters of the process, viz., the casting speed and the heat transfer coefficient (HTC) at the metal-mold contact region. Specifically, the casting speed and the HTC are varied from 40 to 100 mm/min and from 750 to 3000 W/(m2-K), respectively. With the increase of the casting speed, the solidification process is delayed while the solid-shell thickness increased with the increase of the HTC. The predicted results are presented for the solid-shell thickness, the sump depth, the mushy thickness, the surface temperature as well as the non-dimensional turbulent viscosity contours. In addition the temperature fields and velocity profiles with streamlines are also provided.