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The reported mathematical models of gas–liquid flow in single snorkel Rheinstahl–Heraeus (SSRH) are based on the assumption of steady Ar-molten steel flow. The purpose of this paper is to develop a mathematical model to describe the unsteady turbulent flow (CO-Ar-molten steel) with nonequilibrium decarburization reaction.

On the base of the finite volume method, the computational fluid dynamics software CFX is used to predict the unsteady fluid flow, the spatial distributions of CO/argon gas and carbon element. The water model experiment and the industrial experiment are carried out to verify the mathematical models.

A two-way coupling model (T-WCM) based on algebraic slip model is developed to investigate the coupling phenomena. The related results show that T-WCM is more rigorous and accurate than one-way coupling model in predicting carbon content of molten steel. The amount of CO gas, which can enhance turbulent flow and mass transfer, is about three times the argon gas blown into SSRH.

CO gas is the key factor in investigating the transport phenomena. This study fully reveals the truth about the unsteady gas-liquid flow in SSRH. It is necessary to adopt T-WCM based on algebraic slip model to describe the CO-Ar-molten steel flow phenomenon.

The purpose of the present investigation is to compute the circulation flow of a liquid in a closed chamber when the liquid is fired by a gas jet through number of nozzles.

The conservation equations for mass and momentum have been solved in a closed container along with the conservation of volume fraction of the secondary phase in order to take into account the gas phase present in the liquid. The drag force created by the gas on the liquid has been incorporated in the momentum equation as a source term and the resulting equations have been solved numerically using a finite volume technique in an unstructured grid employing a phase coupled pressure linked velocity solver for the pressure correction equation, which is usually known as the Eulerian Scheme for two phase flow solution. An eddy viscosity based k‐ε turbulence model for the mixture was considered to update the fluid viscosity with iterations and capture the turbulence in the overall mixture rather than computing the individual turbulence in both the phases, which was found to be extremely time‐consuming and computationally unstable to some extent.

The model thus developed was tried to predict the circulation flow rate in an experimental setup where air was injected to drive the water in a long U tube setup. The computed circulation flow rate was found to be within 15 percent deviation from the experimentally observed values. The circulation flow rate of water was found to be increasing with the injected airflow rate. After this model validation, circulation flow rate of steel in an industrial size Ruhrstal‐Haraeus (RH)‐degasser was computed by injecting argon into the liquid steel through the up‐leg of the RH vessel. It was found that the circulation flow rate of steel in the RH degasser was increasing when the argon flow was being varied from 800 to 1,600 NL/min, which confirms the industrial findings.

The present computation could not use the energy equation to compute the swelling of the gas bubbles inside the chamber due to huge computing time requirement.

The present computation could compute realistically the circulation flow rate of water in a U tube when fired by a gas jet by using a two‐phase Eulerian model and hence this model can be effectively used for industrial applications where two‐phase flow comes into picture.

The original contribution of the paper is in the use of the state‐of the‐art Eulerian two‐phase flow model to predict circulation flow in an industrial size RH degasser.