Numerical Simulation of Vitrification Processes: Glass Homogeneity by Gas Bubbling Study

A direct induction process using the cold crucible technology has been developed by the French Atomic Commission and AREVA-NC for 25 years. In this process, walls of the crucible are cooled by internal water circulation which protect them from the corrosion and allow higher temperature of the molten glass. Moreover, a mechanical stirrer and air bubbling system promote a good homogeneity of the melt. This study describes how the air bubbling in the glass is modelled in our simulation and enlightens his important role in the homogenisation of the glass during his elaboration. Air bubbling in liquids as viscous as the glass (viscosity up to 10 Pa.s) is not common and specific models have to be built. Two different models are used, first one is a semi-empirical based model, and the second is a two phase model (VOF).