Numerical simulation of multi-size bubbly flow in a continuous casting mold using an inhomogeneous multiple size group model

Abstract

Multi-size bubbly flow in a one-quarter-scale water model of a continuous casting mold was simulated using the inhomogeneous multiple size group (IMUSIG) model. The Sauter mean bubble diameter, gas volume fraction, interfacial area density, turbulence kinetic energy, and velocity field predicted by the IMUSIG and multiple size group (MUSIG) models were compared. The IMUSIG model separated the motions of the small and large bubbles on the basis of two velocity groups, and both models adopted 15 size groups. The results showed that the IMUSIG model better reflected the bubble size distribution near the nozzle. Small bubbles were further transported by the jet flow, which enlarged the bubble cluster range and decreased the gas volume fraction and interfacial area density in the upper part of the submerged entry nozzle, likely diminishing the coalescence rate in this region; consequently, the overestimation of Sauter mean bubble diameter outside the nozzle was corrected. The liquid-phase flow fields predicted by the IMUSIG and MUSIG models were very similar, and the IMUSIG-predicted magnitudes of velocity and turbulence kinetic energy were only slightly lower than the MUSIG predictions; this slight difference is attributable to the expanded bubble cluster range and higher interfacial area density, which weakened the upper recirculation in the IMUSIG model.