Dynamic behaviors of anisodiametric bubbles under effects of horizontal attraction and vertical wake

The present study aims to describe the interaction between rising bubbles of different sizes. Coaxial and triangle bubble configurations were investigated. Bubble sizes ranged from 4.0 mm to 10.0 mm. Three-dimensional unsteady numerical simulations were performed and the volume of fluid multiphase model was employed. The numerical scheme was validated through experimental results. Time-dependent bubble geometry, bubble velocity, and near-bubble flow patterns were obtained. The results show that the participation of lateral bubbles causes coalescence delay. The mergence of bubbles is followed by an immediate decrease in bubble velocity. Liquid flow structures tend to be combined accordingly as the bubbles coalesce. For the triangle configuration, the first coalescence of small bubbles takes place between the trailing bubbles. As bubble size increases, the first coalescence arises between the leading bubble and the left trailing bubble.