Effect of orifice size and bond number on bubble formation characteristics: A CFD study

Abstract

The volume of fluid with the continuum surface force (VOF-CSF) model has been used in the present numerical study to investigate bubble formation and shapes in a bubble column. The effects of orifice sizes ranging from 0.5-1.5 mm on the bubble formation stages (i.e., expansion, elongation, and pinch-off), bubble contact angle, departure diameter, time, and shape of bubble are investigated under a constant inlet velocity (0.2 m/s) boundary condition (BC). It is found that the initial formation of a bubble is dependent on the orifice diameter. Consequently, the formation of the bubble's hemispherical shape at the orifice is faster for a smaller orifice diameter than for a larger orifice diameter which forms a bigger bubble. A leading bubble requires a longer time to detach itself from an orifice in comparison to the next bubble (the second bubble), but interestingly the third bubble detaches much faster than the second. This model was also used to investigate the effect of the Bond number (Bo s ). An increase of the Bond number (Bo s ) from 0.047 to 0.16 speeds up the bubble pinch-off, but a further increase in the Bo s (e.g. 0.17-0.47) slows it down. Based on the simulated cases used in this study, the findings demonstrate the capacity and accuracy of the CFD method in predicting bubble formation characteristics. The findings may be useful in the design of spargers for bubble column reactors.

Coalescence and rising behavior of co‐axial and lateral bubbles in viscous fluid: a CFD study

“…The motivation of the present study is to further investigate bubble characteristics at above ambient temperature or pressure. We have previously studied the effects of the reduced liquid properties on the formation of a bubble from an orifice . The present study will provide insights into rise and coalescence characteristics of two co‐axial air bubbles (i.e.…”

Simulation of bubbling fluidized beds with cohesive particles by incorporating a novel structure‐Based drag model into the two‐fluid model

“…According to the mechanism of bubble growth, it is reflected that the average diameters increase significantly in the lower bed region, but they remain stable in the higher part. With the experimental research developing on BFBs, many correlations which can effectively reflect the relationship of bubble diameter and other local structure parameters have been obtained …”

Methane bubble formation and dynamics in a rectangular bubble column: A CFD study

“…The state of bubble development changes with the alteration in bubble terminal velocity, coalescence and break-up of bubbles [15][16][17][18][19][20]. The air bubble dynamics i.e., bubble shapes, bubble terminal velocity, the wake structure of bubble and coalescence of two and three bubbles in a bubble column filled with different quiescent liquid e.g., water, glycerol-water solution have been extensively studied [21][22][23][24].…”