Simulation and validation of two-phase turbulent flow and particle transport in continuous casting of steel slabs

In continuous steel casting, argon gas is usually injected at the slide gate or stopper rod to prevent clogging, but entrapped bubbles may cause defects in the final product. To better understand this, the flow of molten steel and the transport and capture of argon gas bubbles have been simulated and compared with plant measurements. First, the flow field was solved with an Eulerian k-s model of the steel, which was two-way coupled with a Lagrangian model of the large bubbles using a Discrete Random Walk method to include dispersion of bubbles due to turbulence. The asymmetrical flow pattern predicted on the top surface agreed well with nailboard measurements. Then, the motion and capture of over two million bubbles were simulated using two different capture criteria. Results with the advanced capture criterion agreed well with measurements of the number, locations, and sizes of captured bubbles, especially for larger bubbles. The relative capture fraction of 0.3% was close to the measured 0.2% for 1mm bubbles, and occurred very near the top surface. The model presented here is an efficient tool to study the capture of bubbles and inclusion particles in solidification processes.