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Shapes of Splattered Drops
Sri Vallabha Deevi, Nachiketa Janardan,
Published in American Chemical Society
2017
PMID: 28423278
Volume: 33
   
Issue: 18
Pages: 4592 - 4600
Abstract
Drops that impact and stick to a surface (splattered drops) commonly show noncircular triple lines. Physical or chemical defects on the surface are known to pin the triple line in this static metastable state. We report an experimental study to relate the defect distribution on a surface to the triple-line microstructure of such drops. Triple lines of an ensemble of splattered drops have been imaged on a range of surfaces varying in wetting properties. Local contact angles have been calculated, and the microscale pinning force distribution has been estimated. We propose a novel method of estimating defect strength distribution from the pinning forces, using extreme value analysis. From this analysis, we show that pinning force distributions have finite upper and lower bounds. We show that most common surfaces show both hydrophobic and hydrophilic defects, but their strength distributions are asymmetric in relation to the surface’s advancing and receding angles. In addition, we show that the range of microscopic pinning forces varies linearly with macroscopic contact angle hysteresis but, surprisingly, with a nonzero intercept. We explain the intercept by drawing an analogy to static and dynamic friction. © 2017 American Chemical Society.
About the journal
JournalData powered by TypesetLangmuir
PublisherData powered by TypesetAmerican Chemical Society
ISSN07437463
Open AccessNo
Concepts (21)
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    Contact angle
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    Drops
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    Flux pinning
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    Surface defects
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    CONTACT ANGLE HYSTERESIS
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    DEFECT DISTRIBUTION
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    Extreme value analysis
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    HYDROPHOBIC AND HYDROPHILIC
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    META-STABLE STATE
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    STRENGTH DISTRIBUTION
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    Upper and lower bounds
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    WETTING PROPERTY
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    Wetting
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    Article
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    Drawing
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    Experimental study
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    Human
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    Human experiment
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    Hydrophilicity
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    Hydrophobicity
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    Hysteresis