Shear-induced fragmentation of Laponite suspensions

Abstract : Simultaneous rheological and velocity profile measurements are performed in a smooth Couette geometry on Laponite suspensions seeded with glass microspheres and undergoing the shear-induced solid-to-fluid (or yielding) transition. Under these slippery boundary conditions, a rich temporal behaviour is uncovered, in which shear localization is observed at short times, that rapidly gives way to a highly heterogeneous flow characterized by intermittent switching from plug-like flow to linear velocity profiles. Such a temporal behaviour is linked to the fragmentation of the initially solid sample into blocks separated by fluidized regions. These solid pieces get progressively eroded over time scales ranging from a few minutes to several hours depending on the applied shear rate $\dot{\gamma}$. The steady-state is characterized by a homogeneous flow with almost negligible wall slip. The characteristic time scale for erosion is shown to diverge below some critical shear rate $\dot{\gamma}^\star$ and to scale as $(\dot{\gamma}-\dot{\gamma}^\star)^{-n}$ with $n\simeq 2$ above $\dot{\gamma}^\star$. A tentative model for erosion is discussed together with open questions raised by the present results.
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Article dans une revue
Soft Matter, Royal Society of Chemistry, 2009, 5 (1), pp.3026-3037. 〈10.1039/b906274b〉
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Soumis le : lundi 30 mars 2009 - 14:10:33
Dernière modification le : jeudi 19 avril 2018 - 14:54:03
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Thomas Gibaud, Catherine Barentin, Nicolas Taberlet, Sébastien Manneville. Shear-induced fragmentation of Laponite suspensions. Soft Matter, Royal Society of Chemistry, 2009, 5 (1), pp.3026-3037. 〈10.1039/b906274b〉. 〈ensl-00371654〉



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