Effect of mixture velocity on flow topology inside Taylor plugs in a microchannel: experiments and numerical simulations
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Published version
Author(s)
Pheasey, Charlotte
Chagot, Loïc
Angeli, Panagiota
Kahouadji, Lyes
Matar, Omar K
Type
Journal Article
Abstract
We use microparticle image velocimetry and numerical simulations to study the vortex
evolution in liquid-liquid plug flows in a 400 µm T-junction microchannel. Experiments are
conducted using the [C4mim][T2fN] ionic liquid as the continuous phase and a glycerol water blend as the dispersed phase, giving a dispersed to continuous phase viscosity
ratio, λ, of 0.117. The range of mixture velocities studied is 0.002 − 0.03 m/s, which
corresponds to a capillary number range of Cap ∼ 0.0075 − 0.16. We characterize the
vortical structures based on geometry, vorticity, and circulation times within the plugs.
Good agreement is found between the experimental data and the numerical predictions in
terms of plug length, film thickness, and circulation patterns. The plug length is found to
decrease while the film thickness increases with Cap. Three pairs of vortices are formed
within the plug in a reference frame moving with the steady plug speed. The pairs comprise
a main pair that occupies the central region of the plug and two secondary pairs located
at the plug front and rear. The secondary vortices diminishment with Cap is quantified
based on their geometry and vorticity, subsequently correlated to the critical film thickness
for vortex loss based on the predictions of Balestra et al. [Microfluid. Nanofluid.22, 67
(2018)]. It is found that the front and rear secondary vortex pairs diminish at different rates
depending on Cap. With increasing Cap, based on their size, the rear vortex pair is lost
before the front one, while, based on vorticity, only the front vortex pair is lost.
evolution in liquid-liquid plug flows in a 400 µm T-junction microchannel. Experiments are
conducted using the [C4mim][T2fN] ionic liquid as the continuous phase and a glycerol water blend as the dispersed phase, giving a dispersed to continuous phase viscosity
ratio, λ, of 0.117. The range of mixture velocities studied is 0.002 − 0.03 m/s, which
corresponds to a capillary number range of Cap ∼ 0.0075 − 0.16. We characterize the
vortical structures based on geometry, vorticity, and circulation times within the plugs.
Good agreement is found between the experimental data and the numerical predictions in
terms of plug length, film thickness, and circulation patterns. The plug length is found to
decrease while the film thickness increases with Cap. Three pairs of vortices are formed
within the plug in a reference frame moving with the steady plug speed. The pairs comprise
a main pair that occupies the central region of the plug and two secondary pairs located
at the plug front and rear. The secondary vortices diminishment with Cap is quantified
based on their geometry and vorticity, subsequently correlated to the critical film thickness
for vortex loss based on the predictions of Balestra et al. [Microfluid. Nanofluid.22, 67
(2018)]. It is found that the front and rear secondary vortex pairs diminish at different rates
depending on Cap. With increasing Cap, based on their size, the rear vortex pair is lost
before the front one, while, based on vorticity, only the front vortex pair is lost.
Date Issued
2025-09-01
Date Acceptance
2025-06-24
Citation
Physical Review Fluids, 2025, 10 (9)
ISSN
2469-990X
Publisher
American Physical Society
Journal / Book Title
Physical Review Fluids
Volume
10
Issue
9
Copyright Statement
Published by the American Physical Society Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
License URL
Publication Status
Published
Article Number
094201
Date Publish Online
2025-09-02