Computational Fluid Dynamics Study of Molten Steel Flow Patterns and Particle–Wall Interactions Inside a Slide-Gate Nozzle by a Hybrid Turbulent Model

Melt flow patterns and turbulence inside a slide-gate throttled submerged entry nozzle (SEN) were studied using Detached–Eddy Simulation (DES) model, which is a combination of Reynolds–Averaged Navier–Stokes (RANS) and Large–Eddy Simulation (LES) models. The DES switching criterion between RANS and LES was investigated to closely reproduce the flow structures of low and high turbulence regions similar to RANS and LES simulations, respectively. The melt flow patterns inside the nozzle were determined by k–ε (a RANS model), LES, and DES turbulent models, and convergence studies were performed to ensure reliability of the results. Results showed that the DES model has significant advantages over the standard k–ε model in transient simulations and in regions containing flow separation from the nozzle surface. Moreover, due to applying a hybrid approach, DES uses a RANS model at wall boundaries which resolves the extremely fine mesh requirement of LES simulations, and therefore it is computationally more efficient. Investigation of particle distribution inside the nozzle and particle adhesion to the nozzle wall also reveals that the DES model simulations predict more particle–wall interactions compared to LES model.