Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward the tundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was carried out with the utilization of a 1∶4 scale model. Numerical modelling was carried out in line with the physical modelling to examine details of the flow pattern and rotational effect caused by the upward flow with the commercial CFD (Computational Fluid Dynamics) package environment, FLUENT. The two-equation k-ε model was used to simulate the turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid (VoF) method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations. Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward the tundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modeling was carried out with the utilization of a 1: 4 scale model. Numerical modeling was carried out in line with the physical modeling to examine details of the flow pattern and rotational effect caused by the upward flow with the commercial CFD (Computational Fluid Dynamics) package environment, FLUENT. The two-equation k-ε model was used to simulate the Turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid (VoF) method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.