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Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets
Published on: February 22, 2016
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Pinching Dynamics and Multiple Droplet Generation in Partial Coalescence.
1ThAMeS Multiphase, Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom.
Physical Review Letters
|September 22, 2023
Summary
Partial coalescence occurs when a liquid cylinder pinches off due to Rayleigh-Plateau instability. Surfactants alter droplet formation and thinning dynamics, creating multiple droplets at higher concentrations.
Area of Science:
- Fluid dynamics
- Interfacial phenomena
- Rheology
Background:
- Partial coalescence is a common phenomenon in fluid dynamics.
- Understanding droplet dynamics is crucial for various industrial applications.
Purpose of the Study:
- Investigate the mechanism of liquid cylinder pinch-off during partial coalescence.
- Analyze the influence of surfactants on droplet formation and breakup dynamics.
Main Methods:
- Experimental investigation using drop impact experiments.
- Numerical simulations to model fluid behavior.
- Analysis of neck thinning regimes (inertial and inertial-viscous).
Main Results:
- Rayleigh-Plateau instability drives cylinder pinch-off when height-to-neck ratio exceeds one.
- Surfactants attenuate the liquid cylinder and promote multiple droplet generation.
- Neck thinning transitions from inertial (I) to inertial-viscous (IV) regimes.
- An intermediate regime accelerates thinning at higher surfactant concentrations.
Conclusions:
- The study elucidates the critical role of Rayleigh-Plateau instability in partial coalescence.
- Surfactants significantly modify droplet breakup pathways, enabling control over droplet generation.
- Identified distinct thinning regimes provide insights into the physics of interfacial flows.
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