Large eddy simulations of argon bubble transport and capture in mold region of a continuous steel caster

More than 90% of steel produced globally every year is made using the continuous casting process. In this process, argon gas is usually injected to prevent nozzle clogging. The gas bubbles affect the flow pattern through the bubble drag, and may become entrapped to form defects in the final product. To investigate this problem, we have developed and applied a two-way coupled Eulerian-Lagrangian computational model with Large Eddy Simulations of the turbulent flow and transport and capture of argon bubbles by the solidifying shell. A practical steel caster is considered, and the domain is discretized with more than 16 million hexahedra finite volume cells. The turbulent flow is computed using the Large Eddy Simulation (LES) approach. The trajectories of 1.2 million argon bubbles were tracked by solving the transport equations for each individual bubble. A previously validated particle capture criterion is used to predict the capture of the argon bubbles. The equations are solved on a graphic processing unit (GPU) using an in-house code CUFLOW. The results show that less bubbles are captured in the current LES model when compared with a RANS model. The captured bubble sizes and numbers agree well with plant measurements.