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Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles

J-. B. Salmon·S. Manneville·A. Colin
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Abstract

Using velocity profile measurements based on dynamic light scattering and coupled to structural and rheological measurements in a Couette cell, we present evidences for a shear-banding scenario in the shear flow of the onion texture of a lyotropic lamellar phase. Time-averaged measurements clearly show the presence of structural shear-banding in the vicinity of a shear-induced transition, associated to the nucleation and growth of a highly sheared band in the flow. Our experiments also reveal the presence of slip at the walls of the Couette cell. Using a simple mechanical approach, we demonstrate that our data confirms the classical assumption of the shear-banding picture, in which the interface between bands lies at a given stress $σ^\star$. We also outline the presence of large temporal fluctuations of the flow field, which are the subject of the second part of this paper [Salmon {\it et al.}, submitted to Phys. Rev. E].

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J-. B. Salmon, S. Manneville, A. Colin. 2003-07-24. Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles. https://doi.org/10.1103/physreve.68.051503

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