Effects of Contact Angle on Single and Multiscale Bubble Motions in the Aluminum Reduction Cell

This work deals with the effects of the contact angle as an essential factor in bubble motions underneath downward-facing surfaces of the anode in the aluminum reduction cell. First, a transient three-dimensional (3D) mathematical model is employed to study a single bubble motion with the volume-of-fluid (VOF) method. In addition, a transient 3D model coupled with the discrete phase model and the VOF method is employed to track the microdispersed (∼micrometer or ∼millimeter) and macroscale (∼centimeter) bubbles in various contact angles. A discrete continuum transition model is developed to link the micro- to macroscale of bubbles and analyze the multiscale bubbles co-existing beneath the anode. The predicted gas coverage gives a reasonable match with the experimental data in the literature. The bubble release frequency decreases with increasing the contact angle provided that the contact angle is smaller than 90°, whereas the opposite occurs when the contact angles are larger than 90°.