Single and Multiscale Bubble Motions Beneath an Inclined Downward-Facing Surface in the Aluminum Reduction Cell

Three-dimensional (3D) transient mathematical models are developed to explore the single and multiscale bubble dynamics beneath the inclined downward-facing surface of the anode in an aluminum reduction cell. The single bubble motion is traced by the volume of fluid (VOF) method. For the multiscale bubble, the discrete phase model (DPM) combined with the VOF approach is used to track the dispersed microbubbles’ trajectories and trace the continuous macrobubbles’ surfaces, respectively. A discrete-continuum transition (DCT) model is proposed to convert the dispersed bubbles to continuous ones and deal with the multiscale motions under the inclined anode surface. The predicted results of the sliding bubble velocity and the gas coverage are in a good agreement with the experimental data from the literature. On increasing the inclination angle, the detachment time of the single bubble from the nucleation site decreases while the sliding velocity increases. The gas coverage, bubble size, and thickness of multiscale bubbles decrease on increasing the inclination angle.