Dynamics of partially obstructed breakup of bubbles in microfluidic Y‐junctions

Abstract

For revealing the dynamics of partially obstructed breakup of bubbles in microfluidic Y-junctions, the combination of dimensionless power-law and geometric model was applied to study the effects of capillary number, bubble length, and channel angle on the bubble rupture process. In the squeezing process, the gas-liquid interface curve follows the parabolic model. For the evolution of the bubble neck during breakup, the increase of the bubble length, the channel angle, and the capillary number leads to the decrease of the focus distance α. The chord m increases with the increase of the capillary number and the decrease of the bubble length, and it would reach the maximum value when the channel angle is 90°. In the fast pinch-off stage during bubble breakup, the bubble's neck curve no longer conforms to the parabolic model so the focus and chord no longer exist. For the evolution of the bubble head during breakup, the value of γ approaches 1 with the increase of the capillary number and the bubble length, and with the close of the channel angle to 90°. It is found that the quadrilateral model can be applied for the partially obstructed rupture of bubbles in the symmetrical microfluidic Y-junction.

Review on Microbubbles and Microdroplets Flowing through Microfluidic Geometrical Elements

“…Wang et al [74] and Ziyi et al [75] studied the partial obstructed breakup of bubbles in microfluidic junctions. Wang et al [74] used an asymmetric T-junction, and they concluded that this process can be divided into three stages: squeezing, transition, and pinch-off, according to the evolution of the minimum width of the bubble neck, w m .…”

“…It was also observed that the critical neck width of the breaking bubble is related to the Capillary number (0.0004 ≤ Ca ≤ 0.006) and the length of the original bubble (2.74 ≤ l/w ≤ 4). Very recently, Ziyi et al [75] reported a study about the partially obstructed breakup of bubbles in microfluidic Y-junctions. In Figure 5, it is possible to see the effects of the channel angle (30 • to 150 • ), Capillary number, and bubble length on the bubble rupture process.…”

“…In a study similar to the one condicted by Ziyi et al [75], Chen et al [76] analysed nitrogen-water two-phase flow splitting at microchannel junctions with different branch angles (30 • to 150 • ). The test range covered slug, slug-annular, and annular flow patterns.…”

“…(i) Effect of the channel angle on bubble breakup: (a) 30 • ; (b) 90 • ; (c) 150 • ; (ii) Effect of the Capillary number, Ca, on bubble breakup: (d) Ca = 0.021; (e) Ca = 0.025; (f) Ca = 0.029; (iii) Effect of the bubble length, L, on bubble breakup: (g) L = 1.03 mm; (h) L = 1.24 mm; and, (i) L = 1.42 mm.Adapted with permission from[75].…”

Bubble breakup and boiling heat transfer in Y‐shaped bifurcating microchannels

“…Considerable efforts have been devoted to revealing the bubble/droplet dynamics in the adiabatic Y-shaped bifurcating microchannels, where the breakup stage and flow pattern were recognized as the essential respects. [11][12][13] Xu et al 14 focused on the partially obstructed breakup phenomenon in Y-shaped bifurcating microchannels with various bifurcating angles, bubble lengths, and capillary numbers. Using the high-speed photography, the profiles and evolutions of bubble interface were quantitatively analyzed.…”