Introduction In the present study, mixing characteristics in argon stirred molten steel baths were studied. Vertical injection of argon into a molten steel bath contained in a cylindrical vessel was considered. The problem was formulated on the basis of a multi-component multi-phase model using the Eulerian approach for both phases. Fluctuating motion of the liquid free surface and its irregular shape were taken into account by extending the computational domainabove the initial undisturbed

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... id height. The turbulence in the liquid phase was computedusing the two-equation (k-e) model. Theflow and volume fraction fields in both the gas and liquid phases were predicted numerically. To obtain the mixing time, a tracer liquid was initially injected from top of the vessel, and time evolution of the tracer concentration distribution in the bath was solved. The liquid circulation rate and mixing time were used as measures for intensity of mixing in the bath. 'Mixing time', T~, is defined as the time taken for the tracer concentration to attain, at every nodal location in the system, a value within~5 o/. of the tracer concentration of the well mixed steady state bath. 'The liquid circulation rate' is defined here as the total amount of liquid flowing upward (or downward) through the horizontal mid-plane. In the tracer concentration equation, both the convection and diffusion processes were accounted for. The effects of vessel aspect ratio (Hi/D) and gas injection rates on the mixing time, the liquid circulation rate and on the flow structure in general were investigated. 1 371 2.