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Frozen Patterns in Viscoelastic Droplets Impacting on a Subcooled Surface
Zhijun Jiang1, Wenyuan Zhong1, Youchuang Chao1
1School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Langmuir : the ACS Journal of Surfaces and Colloids
|October 17, 2024
Summary
Viscoelastic polymer droplet impact on cold surfaces shows reduced spreading with higher subcooling and polymer concentration. Unlike pure fluids, polymer droplets exhibit only two freezing modes: freezing and hierarchical cracking.
Area of Science:
- Fluid dynamics
- Materials science
- Surface science
Background:
- Droplet impact on cold surfaces is crucial for aircraft icing and 3D printing.
- Understanding complex fluid droplet dynamics on cold surfaces remains limited.
Purpose of the Study:
- To experimentally investigate the impact, spreading, and freezing of viscoelastic polymer droplets on subcooled substrates.
- To characterize the resulting frozen patterns and identify influencing parameters.
Main Methods:
- Controlled droplet impact experiments using viscoelastic polymer solutions.
- Varying subcooling temperatures and polymer concentrations.
- Analysis of droplet spreading diameter and frozen pattern morphology.
Main Results:
- Maximum droplet spreading diameter decreases with increasing subcooling and polymer concentration.
- Spreading data collapses onto a universal curve governed by inertial, capillary, and viscous forces.
- Polymer droplets exhibit two distinct freezing modes: freezing and hierarchical cracking, unlike pure fluids.
Conclusions:
- A phase diagram was constructed to characterize frozen patterns based on undercooling and polymer concentration.
- Findings offer insights into complex fluid solidification for applications like spray coating and additive manufacturing.
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