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Fabricating High-viscosity Droplets using Microfluidic Capillary Device with Phase-inversion Co-flow Structure
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Spreading of volatile droplets in a humidity-controlled environment
Nayoung Kim1, Pallav Kant2, Devaraj van der Meer1
1Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, University of Twente, 7500 AE Enschede, The Netherlands. nayoungkim516@gmail.com.
Soft Matter
|July 15, 2024
Summary
High humidity alters ethanol droplet spreading, causing faster movement and fingering instability due to hygroscopic and Marangoni effects. This research explores fluid dynamics under varying environmental conditions.
Area of Science:
- Fluid Dynamics
- Physical Chemistry
Background:
- Ethanol droplet spreading on substrates typically forms a uniform film.
- Environmental factors can significantly influence droplet behavior.
Purpose of the Study:
- To investigate the effect of ambient relative humidity on pure ethanol droplet spreading.
- To elucidate the underlying mechanisms, including solutal and thermal Marangoni effects.
Main Methods:
- Deposition of pure ethanol droplets on dry, wettable, and conductive substrates.
- Controlled variation of ambient relative humidity.
- Observation and analysis of droplet spreading dynamics and contact line behavior.
Main Results:
- Increased relative humidity accelerates droplet spreading.
- Higher humidity destabilizes the moving contact line, inducing fingering instability.
- Hygroscopic nature of ethanol and solutal-Marangoni effects are identified as primary drivers.
Conclusions:
- Droplet spreading is significantly influenced by ambient relative humidity.
- The interplay of solutal and thermal Marangoni effects governs the dynamics of hygroscopic droplet spreading.
- Fingering instability arises from humidity-driven destabilization of the contact line.
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