Wall Slip of Soft-Jammed Systems: A Generic Simple Shear Process

From well-controlled long creep tests, we show that the residual apparent yield stress observed with soft-jammed systems along smooth surfaces is an artifact due to edge effects. By removing these effects, we can determine the stress solely associated with steady-state wall slip below the material y...

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Bibliographic Details
Published in:Physical review letters 2017-11, Vol.119 (20), p.208004-208004, Article 208004
Main Authors: Zhang, X, Lorenceau, E, Basset, P, Bourouina, T, Rouyer, F, Goyon, J, Coussot, P
Format: Article
Language:English
Subjects:
Condensed Matter
Fluid Dynamics
Fluid mechanics
Mechanics
Mechanics of materials
Physics
Soft Condensed Matter
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Summary:From well-controlled long creep tests, we show that the residual apparent yield stress observed with soft-jammed systems along smooth surfaces is an artifact due to edge effects. By removing these effects, we can determine the stress solely associated with steady-state wall slip below the material yield stress. This stress is found to vary linearly with the slip velocity for a wide range of materials whatever the structure, the interaction types between the elements and with the wall, and the concentration. Thus, wall slip results from the laminar flow of some given free liquid volume remaining between the (rough) jammed structure formed by the elements and the smooth wall. This phenomenon may be described by the simple shear flow in a Newtonian liquid layer of uniform thickness. For various systems, this equivalent thickness varies in a narrow range (35±15  nm).
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.119.208004