Molten steel flow, slag behaviour and heat transfer in the mould are all major factors controlling internal and surface quality of cast steel products. A model capable of coupling these phenomena under diverse casting conditions (e.g. casting speed, pouring temperature, steel chemistry) is being developed to determine optimal process conditions and minimize defects. A numerical model based on the commercial CFD code FLUENT? is employed to solve the full set of Navier-Stokes Equations coupled with a Volume of Fluid interface tracking technique. The model describes the multiphase air-slag-molten metal system including the prediction of meniscus transient behaviour and powder bed/slag film thickness. The cooling system effects are investigated by including the heat conduction equation right through to the solid mould faces. Slag infiltration and phase transformation inside the shell-mould gap is implicitly determined whilst flux properties are included using published thermo-physical data. Shell growth is calculated in the final stage by means of an enthalpy-based method. A parametric study revealed the strong influence of the cooling channels on shell growth as well as a marked shell thinning caused by the discharging jets as casting speed increases. These phenomena produce heat flux variations in the transverse and longitudinal directions that lead to uneven shell formation. The aim of this investigation is to clarify key features in the casting practice, such as heat flux behaviour and slag film development across the mould length, in order to improve the quality of cast products.
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