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Updated: Jan 11, 2026
07:18
Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
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Dynamics of Solid-Liquid Compound Droplets on Cylindrically Concave Superhydrophobic Surfaces
Niju K Mohammed1, P S Tide1, Franklin R John1
1Department of Mechanical Engineering, School of Engineering, Cochin University of Science and Technology, Cochin 682022, Kerala, India.
Langmuir : the ACS Journal of Surfaces and Colloids
|November 17, 2025
Summary
This study shows that droplet-particle interactions on superhydrophobic concave surfaces reduce compound droplet spreading and contact time. These findings offer insights into controlling droplet behavior on curved substrates for various applications.
Area of Science:
- Fluid dynamics
- Surface science
- Materials science
Background:
- Droplet-particle interactions are crucial for applications like diagnostics and drug delivery.
- Understanding droplet behavior on curved surfaces is essential for advanced material design.
Purpose of the Study:
- To investigate the dynamics of compound droplet formation and lift-off on superhydrophobic concave surfaces.
- To analyze the influence of surface concavity on droplet spreading and residence time.
Main Methods:
- Performed single-droplet impact experiments with deionized water droplets on glass beads placed on concave superhydrophobic surfaces.
- Utilized high-speed visualization to capture droplet dynamics across a range of Weber numbers (8.20-57.10).
- Developed theoretical scaling models for droplet extension and lift-off, incorporating curvature effects.
Main Results:
- Compound droplet formation and lift-off were observed on concave surfaces.
- Increased surface concavity (δ) led to reduced maximum spreading diameter (βmax) and shorter residence times.
- Concave surfaces suppressed spreading and decreased contact time by up to 30% compared to flat surfaces.
- A new scaling law for droplet extension on concave surfaces was proposed, reducing to the established law for flat surfaces.
Conclusions:
- Surface concavity significantly influences compound droplet dynamics, suppressing spreading and reducing residence time.
- The developed theoretical models accurately predict droplet behavior on curved superhydrophobic substrates.
- Findings provide valuable insights for manipulating compound droplets on curved surfaces in microfluidics and material science.
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