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The ejection of large non-oscillating droplets from a hydrophobic wedge in microgravity

Authors :
Logan J. Torres
Mark M. Weislogel
Source :
npj Microgravity, Vol 7, Iss 1, Pp 1-10 (2021)
Publication Year :
2021
Publisher :
Nature Portfolio, 2021.

Abstract

Abstract When confined within containers or conduits, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, system geometry, and initial conditions. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration and ejection of large inertial-capillary drops confined between tilted planar hydrophobic substrates (a.k.a., wedges). In our experiments, the brief nearly weightless environment of a 2.1 s drop tower allows for the study of such capillary dominated behavior for up to 10 mL water drops with migration velocities up to 12 cm/s. We control ejection velocities as a function of drop volume, substrate tilt angle, initial confinement, and fluid properties. We then demonstrate how such geometries may be employed as passive no-moving-parts droplet generators for very large drop dynamics investigations. The method is ideal for hand-held non-oscillatory ‘droplet’ generation in low-gravity environments.

Details

Language :
English
ISSN :
23738065
Volume :
7
Issue :
1
Database :
Directory of Open Access Journals
Journal :
npj Microgravity
Publication Type :
Academic Journal
Accession number :
edsdoj.42464be118a0475397d696807ab246c3
Document Type :
article
Full Text :
https://doi.org/10.1038/s41526-021-00182-4