Manipulation of jet breakup length and droplet size in axisymmetric flow focusing upon actuation

Abstract

External sinusoidal actuation is employed in the axisymmetric flow focusing (AFF) for generating uniform droplets in the jetting mode. The perturbations propagating along the meniscus surface can modulate the rupture of the liquid jet. Experiments indicate that the jet breakup length and the resultant droplet size can be precisely controlled in the synchronized regime, which are further confirmed by the scaling law. The finding of this study can help for better understanding of the underlying physics of actuation-aided AFF, and this active droplet generation method with fine robustness, high productivity, and nice process control would be advantageous for various potential applications.

Time-resolved velocity and pressure field quantification in a flow-focusing device for ultrafast microbubble production

“…To the best of our knowledge, no studies have investigated the effect of forced oscillations of the liquid flow on the timescale of the production frequency of bubbles. Such studies have however been conducted for droplets, numerically by Mu et al [28] and experimentally by Yang et al [29]. The authors find that the droplet production frequency will lock into the actuation frequency as long as the two are not too different; in that case the production becomes polydisperse but periodic (binodal, Hopf bifurcation) or even completely unpredictable, probably chaotic.…”

“…The authors find that the droplet production frequency will lock into the actuation frequency as long as the two are not too different; in that case the production becomes polydisperse but periodic (binodal, Hopf bifurcation) or even completely unpredictable, probably chaotic. Furthermore, actuating both inner and outer liquid during droplet production has an effect on droplet size [28,29]. If velocity fluctuations are strong enough to play a role in the coupling between several flow-focusing nozzles for bubble production, one could expect a favorable locking to one and the same frequency, although the exact phase behavior may be both, either beneficial of unfavorable.…”

A Microcapsule‐Assistant Self‐Healing Magnesium Battery Cathodes

“…The microfluidic system is similar to our previous reports. [ 26,33 ] In this study, 0.5 g of branched polyethylene diamine was dissolved in 25 mL of ethanol, then 1 g of carbon nanospheres were added under stirring, forming the inner phase of the microfluidic system. 2‐Hydroxy‐2‐methylpropiophenone of 0.2 g weight and trimethanol propane ethoxy ester triacrylate of 20 g weight were dissolved in 20 mL of ethanol, and heated in an oven at 70 °C for 12 h. After evaporating the ethanol, the middle phase was obtained.…”

“…The microcapsules were prepared using a microfluidic approach. [ 26,27 ] The self‐healing process is as follows: when the cathode cracks, the microcapsules would break and release the core materials containing carbonized carbon nanospheres in branched polyethylene diamine hydrogel into the cracks. The released core is conductive, so that the pathway for the transport of electrons could be repaired.…”

Time-resolved velocity and pressure field quantification in a flow-focusing device for ultrafast microbubble production

“…[28] and experimentally by Yang et al [29]. The authors find that the droplet production frequency will lock into the actuation frequency as long as the two are not too different, in that case the production becomes polydisperse but periodic (binodal, Hopf bifurcation) or even completely unpredictable, probably chaotic.…”