Application of the hybrid LES-RANS model in the fluid flow simulation of molten steel in a mold

A novel hybrid LES-RANS (large eddy simulation-Reynold average Navier-Stokes) turbulent model was introduced to simulate fluid flow in a mold. The model employs the method of grid filtering which calculates the Navier-Stokes equation directly for large-scale eddies and calculates the standard k-ε equations for small-scale fluctuations by modifying the turbulent viscosity coefficient to simulate the flow field of molten steel. The modified eddy viscosity in the LES-RANS model can avoid the excessive diffusive nature of the RANS model and capture the transient features of turbulent flow. In this work, turbulent flow in a liquid metal (GaInSn) model of continuous casting was measured by ultrasonic Doppler velocimetry (UDV). It is shown that compared with the RANS model, the results of the LES-RANS model are more identical with measured data, so the LES-RANS model can more accurately predict the turbulence structure. The characteristics of transient flow in the mold show that bias flow at the two sides of the nozzle changes periodically and the period is about 5 s.