Pressure-driven microfluidic droplet formation in Newtonian and shear-thinning fluids in glass flow-focusing microchannels

Qi Chen, Jingkun Li, Yu Song, Bin Chen, David M Christopher, Xuefang Li

Research output: Contribution to journalArticlepeer-review

Abstract

Pressure-driven microdroplet formation was experimentally investigated in glass flow-focusing devices using micro-imaging. The observations illustrated the effects of some important factors affecting the droplet formation, including the channel geometry, two-phase flow rates and non-Newtonian behavior of the continuous phase. Although the droplet formation dynamics showed some different characteristics in different geometries, self-similarities of the dispersed thread were found in both devices for various initial conditions by normalizing the thread length and time. When power-law shear-thinning fluids were used as the continuous phase, the growth of the dispersed thread was still self-similar, but the relationship became linear rather than power-law as with the Newtonian continuous phase. The droplet shape also changed for droplet generated in shear-thinning fluids, so a deformation index (D.I.) was defined to describe the shape differences. Finally, a previously presented prediction model was validated by the experimental data with good agreement.

Original languageEnglish
Article number103648
JournalInternational Journal of Multiphase Flow
Volume140
Early online date28 Mar 2021
DOIs
Publication statusPublished - 1 Jul 2021

Keywords

  • Flow-focusing devices
  • Microdroplet formation
  • Newtonian fluids
  • Self-similarity
  • Shear-thinning fluids

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