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Dynamic flotation conditions for elongated cylinders on liquid surfaces
Bingqiang Ji1, Zuozhou Tang1, Qiang Song1
1Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, 100084 Beijing, China.
Journal of Colloid and Interface Science
|April 3, 2019
Summary
Dynamic flotation of elongated cylinders is crucial for understanding water-walking insects. Unlike spheres, all elongated cylinders with positive contact angles can float, with hydrophilic ones showing superior buoyancy.
Area of Science:
- Fluid dynamics
- Biophysics
- Surface science
Background:
- Static flotation of elongated cylinders is understood.
- Dynamic flotation behavior after liquid contact, relevant to water-walking insects, remains unclear.
Purpose of the Study:
- To reveal the dynamic flotation behavior of elongated horizontal cylinders after zero-velocity contact with a liquid surface.
- To determine the conditions for dynamic flotation and establish a theoretical framework.
Main Methods:
- Established and solved the motion equation for elongated horizontal cylinders upon liquid surface contact.
- Investigated the influence of Bond number and contact angle on flotation behavior.
Main Results:
- Determined limiting density ratios for dynamic flotation, showing increased hydrophobicity enhances floatability up to 120° contact angles.
- Developed an asymptotic formula for limiting density ratio based on energy balance, showing good agreement with theoretical results.
- Observed that all elongated cylinders with contact angles >0° exhibit floatability, outperforming small spheres.
Conclusions:
- Elongated cylinders demonstrate superior floatability compared to small spheres, particularly hydrophilic ones.
- Findings provide insights into the survival mechanisms of water-walking insects in diverse aquatic environments.
- The study advances the understanding of dynamic buoyancy for elongated objects.
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