Ultrasound velocimetry in a shear-thickening wormlike micellar solution: Evidence for the coexistence of radial and vorticity shear bands

Abstract : We carried out pointwise local velocity measurements on 40mM cetylpyridinium chloride-sodium salicylate (CPyCl-NaSal) wormlike micellar solution using high-frequency ultrasound velocimetry in a Couette shear cell. The studied wormlike solution exhibits Newtonian, shear-thinning and shear-thickening rheological behavior in a stress-controlled environment. Previous rheology, flow visualization and small-angle light/neutron scattering experiments in the shear-thickening regime of this system showed the presence of stress-driven alternating transparent and turbid rings or vorticity bands along the axis of the Couette geometry. Through local velocity measurements we observe a homogeneous flow inside the 1mm gap of the Couette cell in the shear-thinning (stress-plateau) region. Only when the solution is sheared beyond the critical shear stress (shear-thickening regime) in a stress-controlled experiment, we observe inhomogeneous flow characterized by radial or velocity gradient shear bands with a highly sheared band near the rotor and a weakly sheared band near the stator of the Couette geometry. Furthermore, fast measurements performed in the shear-thickening regime to capture the temporal evolution of local velocities indicate coexistence of both radial and vorticity shear bands. However the same measurements carried out in shear rate controlled mode of the rheometer do not show such rheological complexity.
Complete list of metadatas

Cited literature [43 references]  Display  Hide  Download

https://hal-ens-lyon.archives-ouvertes.fr/ensl-00526262
Contributor : Sébastien Manneville <>
Submitted on : Thursday, October 14, 2010 - 10:29:22 AM
Last modification on : Wednesday, November 20, 2019 - 2:47:53 AM
Long-term archiving on : Saturday, January 15, 2011 - 2:39:29 AM

File

Herle_EPJE_soumis.pdf
Files produced by the author(s)

Identifiers

Collections

Citation

Vishweshwara Herle, Sébastien Manneville, Peter Fischer. Ultrasound velocimetry in a shear-thickening wormlike micellar solution: Evidence for the coexistence of radial and vorticity shear bands. European Physical Journal E: Soft matter and biological physics, EDP Sciences: EPJ, 2008, 26 (1-2), pp.3-12. ⟨10.1140/epje/i2007-10304-3⟩. ⟨ensl-00526262⟩

Share

Metrics

Record views

129

Files downloads

248