Large eddy simulation for unsteady turbulent flow in thin slab continuous casting mold

Abstract

Unsteady turbulent flow in the thin slab continuous casting mold has been computed using the large eddy simulations (LES). The cassette filter function is used to deal with unsteady Navier-Stokes equation, and the Smagorinsky-Lilly sub-grid scale model is used to calculate the dissipative effort of the unresolved small eddies. And this LES model has been validated with the measurements of the particle image velocimetry (PIV) and the ultrasonic flaw detection. The computational domain includes the entire submerged entry nozzle (SEN) starting from the tundish exit and the extended mold region. The results show the characteristics of the unsteady turbulent flow in the thin slab continuous casting processes, such as the vortices distribution and the formation, development, shedding and fracture process of the large eddy coherent structures. The simulation also shows that the turbulent flow is asymmetric even if the nozzle and mold is perfect symmetric in geometry. The flow deviation of the molten steel in the mold is inevitable existence. And the interactions of flows in two sides of nozzle also can cause intensity velocity fluctuation near the meniscus. With the development of the unsteady turbulent flow, the flow deviation of the molten steel in the thin continuous casting strand presented periodic change, and the period is about 40 s. © Right.