Bubble Motion and its Surrounding Liquid Motion through the Collision of a pair of Bubbles

Abstract

The interaction between bubble motion and its surrounding liquid motion through a collision of a pair of zigzagging bubbles in a rest water column was experimentally investigated. A pair of hypodermic needles and a bubble generator utilizing pressure oscillation were employed in order to exactly extract and highly reproduce the interaction between liquid-phase motion and bubble motion. The recursive cross-correlation PIV technique made it possible to obtain the accurate velocity field of surrounding liquid motion around a pair of bubbles. The vorticity field around a pair of bubbles was calculated from the results of velocity field. First, various kinds of interactions (e.g. bouncing and coalescence) were found out from the results of bubble motion (e.g. velocity) after a collision. We classified such interactions of a pair of bubbles using the dimensionless number l/d. Second, we investigated surrounding liquid motion about the two cases of interactions after the bouncing. One is that only horizontal velocity of bubble decreased after the collision, the other is that both horizontal and vertical velocity decreased. At the former case, the vortical region generated at the rear of a pair of bubbles. Therefore as the reason for the decrease of bubble velocity, the shedding area of hairpin-like vortex is restricted. At the latter case, bubble wake flows into the area between bubbles and vortical region doesn't generate under bubbles after the collision. Hence, bubble wake overtakes a pair of bubbles after the collision, then, bubble velocity decreased.

Influence of Bubble Bouncing on Mass Transfer and Chemical Reaction

“…For the accurate investigation of mass transfer during bubble bouncing, an experimental setup is necessary that allows the generation of bubbles with reproducible shapes and trajectories. This can be achieved by using a hypodermic needle for bubble injection according to Sone et al [11]. With this kind of orifice the bubble interface is deformed at the exact same position each time a bubble is generated, which leads to a reproducible shape and bubble trajectory.…”

“…Consequently, the interface deformations should be studied first in experiments with direct, well-defined bubble-bubble interaction. Despite the fact that bubble interactions have been already investigated by other working groups with respect to the fluid mechanical mechanisms [7][8][9][10][11] or the qualitative influence on mass transfer [12], the knowledge on the quantitative influence on mass transfer and chemical reaction is still marginal.…”

Hydrodynamic interaction of bubbles rising side-by-side in viscous liquids

“…Finally, recent 3D DNS simulations by Gumulya et al (2017) again revealed the existence of an equilibrium distance, leaving the discussion open to debate. The simultaneous release of two bubbles rising side-byside has been studied by a large number of researchers (Kok 1993;Van Wijngaarden 1993, 2005Duineveld 1995Duineveld , 1998Legendre et al 2003;Sone et al 2008;Sanada et al 2009;Hallez and Legendre 2011;Zhang et al 2019). Van Wijngaarden (1993) calculated the interaction of a pair of bubbles using a two-bubble probability density function and compared his results to the experimental data of Kok (1993).…”

Test System for the Investigation of Reactive Taylor Bubbles

“…To get the stochastic behavior of a bubble under control, there are techniques available which, e.g., use a well-defined bubble detachment that leads to a reproducible helical bubble movement [5,6], or create a vertically rising bubble by increased viscosity [7]. One disadvantage of these techniques is a short residence time of the bubble in the setup that prevents the establishment of steady conditions, necessary for many highly sensitive concentration measurement systems like Raman spectroscopy.…”