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Motions of droplets on hydrophobic model surfaces induced by thermal gradients

We have studied experimentally the motions of liquid droplets deposited on nonwettable surfaces (silanized silicon wafers) submitted to horizontal thermal gradients partial differential T. Systematic measurements of the drift velocity V for different droplet radii R show the following: (i) the dropl...

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Bibliographic Details
Published in:Langmuir 1993-08, Vol.9 (8), p.2220-2224
Main Authors: Brzoska, J. B, Brochard-Wyart, F, Rondelez, F
Format: Article
Language:English
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Summary:We have studied experimentally the motions of liquid droplets deposited on nonwettable surfaces (silanized silicon wafers) submitted to horizontal thermal gradients partial differential T. Systematic measurements of the drift velocity V for different droplet radii R show the following: (i) the droplets move only above a critical radius R sub(c) which depends on contact angle hysteresis and is inversely proportional to partial differential T; (ii) above R sub(c), V increases linearly with R and partial differential T; (iii) for large radii R (droplets flattened by gravity), V reaches a saturation value. The droplet contour is no longer circular, but presents two straight-line segments in the direction of partial differential T. The flow patterns at the free surface of the droplets have been monitored by video recording the displacement of floating particles.
ISSN:0743-7463
1520-5827
DOI:10.1021/la00032a052