Adhesion of yield stress fluids

The different regimes of flow when separating two solid rough surfaces in contact via a layer of a simple yield stress fluid are identified. Generic scalings for the adhesion energy and for the geometrical characteristics of the final deposits (after separation) as a function of the initial aspect r...

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Bibliographic Details
Published in:Soft matter 2010-01, Vol.6, p.1343-1351
Main Authors: Barral, Q., Ovarlez, G., Chateau, X., Boujlel, J., Rabideau, B., Coussot, P.
Format: Article
Language:English
Subjects:
Condensed Matter
Materials Science
Physics
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Summary:The different regimes of flow when separating two solid rough surfaces in contact via a layer of a simple yield stress fluid are identified. Generic scalings for the adhesion energy and for the geometrical characteristics of the final deposits (after separation) as a function of the initial aspect ratio of the sample are found. We show that there is a strong pinning effect which might be at the origin of an adhesion energy significantly larger (by a factor about 2) than that estimated from the lubrication theory. We also observe that the conditions of development of viscous fingering are not at all predicted by the conventional Saffman-Taylor instability theory taking into account the specific non-Newtonian character of the fluid. This again suggests that for pastes the pinning effect plays a significant stabilizing role.
ISSN:1744-683X
1744-6848
DOI:10.1039/b922162j