Lattice Boltzmann Method Modeling of the Evolution of Coherent Vortices and Periodic Flow in a Continuous Casting Mold

Abstract

Transient phenomena and vortex structures throughout the mold are simulated using a lattice Boltzmann method (LBM) coupled with large eddy simulation (LES) using a free surface model under steady operating conditions. The accuracy of the LBM-LES model has been verified by comparing the simulated velocities with published experimental values. The current work focuses on the evolution of the vortex structure in internal flow inside the submerged entry nozzle (SEN) jet flow and the turbulent flow near the wall of the mold. The results show various types of vortex structures with different directions are presented during the jet impingement, including the “ring, rib, and horseshoe”-like shaped vortices in the simulation, resulting in complex turbulent flow near the wall of the mold. Vortices structures are then identified and compared by different vorticial criteria, including vortex methods (ω), Q method, λ2 method (Lambda-2), Δ method (Delta), and Ω method (Omega). The formation, development, and dissipation of the vortex structures and their effects on turbulence are investigated. The results indicate that the turbulent flow (viscosity) can reflect changes in asymmetric vortices structures and flow patterns (via crossflow), which can reflect the periodical flow in the mold. Flow oscillation frequencies are mainly concentrated in the range of 0.3 Hz in this simulation. The oscillations are not a simple combination of frequency modes of crossflow in the mold. These new studies can elucidate the mechanism of vortex structure distributions in representative flow regions of the continuous casting mold.