title: Alternating vorticity bands in a solution of wormlike micelles.
abstract: We report on structural characterization of vorticity bands formed in a wormlike micellar solution by Rheo--small-angle neutron scattering and video imaging experiments. Below a critical shear stress tau{c} in Newtonian and shear-thinning regime, only a minor flow alignment of the micelles is observed. Above tau{c}, in the shear-thickening regime, alternating transparent and turbid bands are formed. Triggered small-angle neutron scattering shows different anisotropic patterns in both bands indicating strongly aligned structures. By high-speed video imaging, we show that such an alignment of micelles does not correspond to a phase of lower viscosity.
authors.affiliation: Institute of Food Science and Nutrition, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Vishweshwara
authors.initials: V
authors.lastname: Herle
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohlbrecher
authors.forename: Bruno
authors.initials: B
authors.lastname: Pfister
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.forename: Erich J
authors.initials: EJ
authors.lastname: Windhab