We derived equations and closed-form solutions of transit time for a viscous droplet squeezing through a small circular pore with a finite length at microscale under constant pressures. Our analyses were motivated by the vital processes of biological cells squeezing through small pores in blood vessels and sinusoids and droplets squeezing through pores in microfluidics. First, we derived ordinary differential equations (ODEs) of a droplet squeezing through a circular pore by combining Sampson flow, Poiseuille flow, and Young–Laplace equations and took into account the lubrication layer between the droplet and the pore wall. Second, for droplets wetting the wall with small surface tension, we derived the closed-form solutions of transit time. For droplets with finite surface tension, we solved the original ODEs numerically to predict the transit time. After validations against experiments and finite element simulations, we studied the effects of pressure, viscosity, pore/droplet dimensions, and surface tension on the transit time. We found that the transit time is inversely linearly proportional to pressure when the surface tension is low compared to the critical surface tension for preventing the droplet to pass and becomes nonlinear when it approaches the critical tension. Remarkably, we showed that when a fixed percentage of surface tension to critical tension is applied, the transit time is always inversely linearly proportional to pressure, and the dependence of transit time on surface tension is nonmonotonic. Our results provided a quick way of quantitative calculations of transit time for designing droplet microfluidics and understanding cells passing through constrictions.
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August 2023
Research Article|
August 18 2023
Analytical theory for a droplet squeezing through a circular pore in creeping flows under constant pressures
Zhengxin Tang (唐正昕)
;
Zhengxin Tang (唐正昕)
(Formal analysis, Investigation, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago
, 1200 W Harrison St, Chicago, Illinois 60607, USA
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François Yaya
;
François Yaya
(Investigation, Writing – review & editing)
2
Aix Marseille Univ, CNRS, (Centre Interdisciplinaire de Nanoscience de Marseille) CINAM, Turing Centre for Living Systems
, Marseille, France
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Ethan Sun
;
Ethan Sun
(Formal analysis, Investigation, Visualization, Writing – original draft)
3
Phillips Academy
, 180 Main St, Andover, Massachusetts 01810, USA
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Lubna Shah;
Lubna Shah
(Formal analysis, Investigation, Visualization, Writing – original draft)
1
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago
, 1200 W Harrison St, Chicago, Illinois 60607, USA
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Jie Xu (徐杰)
;
Jie Xu (徐杰)
(Writing – review & editing)
1
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago
, 1200 W Harrison St, Chicago, Illinois 60607, USA
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Annie Viallat
;
Annie Viallat
(Funding acquisition, Project administration, Supervision, Writing – review & editing)
2
Aix Marseille Univ, CNRS, (Centre Interdisciplinaire de Nanoscience de Marseille) CINAM, Turing Centre for Living Systems
, Marseille, France
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Emmanuèle Helfer
;
Emmanuèle Helfer
(Funding acquisition, Project administration, Supervision, Writing – review & editing)
2
Aix Marseille Univ, CNRS, (Centre Interdisciplinaire de Nanoscience de Marseille) CINAM, Turing Centre for Living Systems
, Marseille, France
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Zhangli Peng (彭张立)
Zhangli Peng (彭张立)
a)
(Conceptualization, Formal analysis, Funding acquisition, Investigation, Project administration, Software, Supervision, Writing – original draft, Writing – review & editing)
1
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago
, 1200 W Harrison St, Chicago, Illinois 60607, USA
a)Author to whom correspondence should be addressed: zhpeng@uic.edu
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a)Author to whom correspondence should be addressed: zhpeng@uic.edu
Physics of Fluids 35, 082016 (2023)
Article history
Received:
April 28 2023
Accepted:
July 28 2023
Citation
Zhengxin Tang, François Yaya, Ethan Sun, Lubna Shah, Jie Xu, Annie Viallat, Emmanuèle Helfer, Zhangli Peng; Analytical theory for a droplet squeezing through a circular pore in creeping flows under constant pressures. Physics of Fluids 1 August 2023; 35 (8): 082016. https://doi.org/10.1063/5.0156349
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