Computational fluid dynamics (CFD) simulations of molten steel flow patterns and particle-wall adhesion in continuous casting of steels

In this research, the measurements of clog deposit thickness on the interior surfaces of a continuous casting nozzle were compared with Computational Fluid Dynamics (CFD) predictions of melt flow patterns and particle-wall interactions to identify the mechanisms of nozzle clogging. A hybrid turbulent approach, Detached Eddy Simulation (DES), was configured to simulate both turbulent structures and particle-wall interactions inside the nozzle accurately. For experimental measurements of nozzle clogging, a nozzle received from industry was encased in epoxy and carefully sectioned to allow measurement of the deposit thickness on the internal surfaces of the nozzle. CFD simulations of melt flow patterns and particle-wall adhesion inside the nozzle were performed applying the geometry and operating conditions of the industrial test. The simulation results indicated that the hybrid DES model incorporates both advantages of Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models which are suitable for modeling wall bounded and transient turbulent flows, respectively. Also, the CFD results showed that the convergent areas of the interior cross section of the nozzle increased the velocity and turbulence of the steel flow inside the nozzle, and decreased the clog deposit thickness locally in those areas. The simulations predicted a higher rate of attachment of particles in the divergent area between two convergent sections of the nozzle, which matched the observations made in the industrial nozzle measurements. Additionally, a mathematical model is proposed for adhesion of particles, to the nozzle wall. This model provides a particle-wall adhesion criterion by considering the presence of external forces, physical characteristics of both wall and particle (e.g. hardness, Young\u27s modules), and the effect of internal forces (e.g. Van Der Waals) --Abstract, page iv