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Updated: Jun 3, 2026
08:49
Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions
Published on: February 17, 2019
Wetting of a drop on a sphere
1Physics of Complex Fluids, IMPACT and MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. h.b.eral@utwente.nl
Langmuir : the ACS Journal of Surfaces and Colloids
|April 7, 2011
Summary
The study reveals that a partially engulfing drop morphology is always more energetically favorable on a sphere, regardless of contact angle or volume. Electrowetting (EW) was used to manipulate contact angles for this analysis.
Area of Science:
- Physics
- Materials Science
- Surface Science
Background:
- Understanding drop behavior on curved surfaces is crucial in various scientific and industrial applications.
- The interplay between surface geometry, interfacial tension, and external stimuli like electrowetting (EW) dictates equilibrium morphologies.
- Previous studies have primarily focused on planar surfaces, leaving non-planar geometries less explored.
Purpose of the Study:
- To experimentally and analytically investigate the equilibrium drop morphology on a sphere.
- To determine the influence of contact angle and drop volume on the drop's shape.
- To validate the application of electrowetting (EW) and the Lippmann-Young equation on curved surfaces.
Main Methods:
- A drop-on-sphere geometry was created using a water drop on a dielectric-coated sphere in an oil bath.
- Electrowetting (EW) was employed to precisely control the water drop's contact angle by varying applied voltage.
- Analytical calculations of effective interfacial energy were performed for competing "completely engulfing" and "partially engulfing" morphologies.
Main Results:
- The study validated the use of electrowetting (EW) and the Lippmann-Young equation for non-flat surfaces, showing consistent EW response across different drop volumes.
- Experimental results were compared with analytical calculations of interfacial energy for different drop morphologies.
- The "partially engulfing" morphology was consistently found to be energetically more favorable than the "completely engulfing" morphology.
Conclusions:
- The "partially engulfing" morphology represents the energetically preferred state for a drop on a sphere across all tested contact angles and drop volumes.
- This research provides valuable insights into the physics of liquid drops on curved surfaces, with implications for microfluidics and coating technologies.
- The findings confirm the applicability of electrowetting for precise control of liquid interfaces on spherical substrates.
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