Two-dimensional volume of fluid simulation studies on single bubble formation and dynamics in bubble columns

In this paper, the volume of fluid (VOF) model in conjunction with continuum surface force (CSF) model was used to numerically investigate the single bubble formation and dynamics in the bubble columns on the software platform of Fluent 6.3. A set of transient conservation equations of mass and momentum taking surface tension and gravitational force effects into consideration were solved by pressure implicit splitting operator (PISO) algorithm and a piecewise linear interface calculation (PLIC) was applied to characterize the behavior of gas–liquid interface movement in the VOF method. The simulation results of bubble formation and dynamics compare well with available literature results. The effects of physical properties including surface tension, liquid viscosity and density, gas or liquid operation conditions and orifice size on the single bubble generation, detachment, rising and coaxial bubble coalescence were systematically analyzed, and the effect of superficial liquid velocity on single bubble behavior was especially discussed. It is found that non-zero superficial liquid velocity enhances the bubble detachment, decreases the bubble size, and delays the coaxial bubble coalescence obviously. Increasing superficial liquid velocity largely raises the velocity of the leading bubble and enlarging orifice gas velocity mainly accelerates the second bubble of two coalescence bubbles.