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arXiv · 1201.6259

Criteria for shear banding in time-dependent flows of complex fluids

Robyn L. Moorcroft·Suzanne M. Fielding
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Abstract

Within a highly generalised theoretical framework for the flow properties of complex fluids, we study the onset of shear banding in the three most common time-dependent experimental protocols: step stress, step strain and shear startup. By means of a linear stability analysis we derive a fluid-universal criterion for the onset of banding, separately for each protocol, that depends only on the shape of the experimentally measured time-dependent rheological response function, independent of the constitutive law and internal state variables of the particular fluid in question. Our predictions thus have the same status, in these time-dependent flows, as the widely known criterion for banding in steady state (of negatively sloping shear stress vs. shear rate). We support them with simulations of the rolie-poly model of polymeric fluids, the soft glassy rheology model, and a fluidity model.

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Robyn L. Moorcroft, Suzanne M. Fielding. 2012-01-30. Criteria for shear banding in time-dependent flows of complex fluids. https://doi.org/10.1103/physrevlett.110.086001

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