UMR 5672

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Transient Shear Banding in a Simple Yield Stress Fluid

T. Divoux, D. Tamarii, S. Manneville

Collaboration : C. Barentin (LPMCN, Universite de Lyon),

We report a large set of experimental data which demonstrates that a simple yield stress fluid, i.e., which does not present aging or thixotropy, exhibits transient shear banding before reaching a steady state characterized by a homogeneous, linear velocity profile. The duration of the transient regime decreases as a power law with the applied shear rate. This power-law behavior, observed here in carbopol dispersions, does not depend on the gap width and on the boundary conditions for a given sample preparation. For shear rates smaller than 0.1 1/s, heterogeneous flows could be observed for as long as 10^5 s. These local dynamics account for the ultraslow stress relaxation observed at low shear rates. 

T. Divoux, D. Tamarii, C. Barentin, and S. Manneville, Phys. Rev. Lett. 104, 208301 (2010)