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Jet or wet? Droplet post-impact regimes on concave contours
Shubham Agrawal1, Gargi Khurana2, Devranjan Samanta2
1Hydrodynamics and Thermal Multiphysics Lab (HTML), Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
The European Physical Journal. E, Soft Matter
|October 2, 2023
Summary
This study examines droplet impact on grooved surfaces, finding that wettability significantly influences recoiling dynamics. Higher impact energy (Weber number) increases spreading but reduces droplet height, while jet velocity is most affected by surface properties.
Area of Science:
- Fluid dynamics
- Surface science
- Microscale phenomena
Background:
- Droplet collision dynamics are crucial for applications like printing and coating.
- Surface wettability and geometry significantly alter droplet-substrate interactions.
- Understanding post-impact behavior is key to controlling fluid behavior on structured surfaces.
Purpose of the Study:
- Investigate droplet impact on hydrophilic and superhydrophobic concave grooves.
- Analyze the influence of impact Weber number and surface wettability on post-collision hydrodynamics.
- Quantify jet velocity, spreading width, and film thickness.
Main Methods:
- Experimental investigation of droplet impact on specifically designed concave grooves.
- Systematic variation of impact conditions (Weber number) and surface properties (wettability).
- Development and validation of a semi-analytical model for jet velocity prediction.
Main Results:
- Spreading width increases with Weber number, while south-pole film thickness decreases.
- Surface wettability plays a more significant role during the recoiling stage than spreading.
- Jet velocity increases with Weber number, particularly on superhydrophobic surfaces, and a model was proposed.
- Groove concavity inversely affects spreading width and south-pole height.
Conclusions:
- Droplet impact outcomes (wetting vs. jetting) depend on impact conditions and surface properties.
- The study provides insights into controlling droplet behavior on textured surfaces.
- A validated semi-analytical framework aids in predicting jet velocity evolution.
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