title: Interfacially driven instability in the microchannel flow of a shear-banding fluid.
abstract: Using microparticle image velocimetry, we resolve the spatial structure of the shear-banding flow of a wormlike micellar surfactant solution in a straight microchannel. We reveal an instability of the interface between the shear bands, associated with velocity modulations along the vorticity direction. We compare our results with a detailed theoretical study of the diffusive Johnson-Segalman model. The quantitative agreement obtained favors an instability scenario previously predicted theoretically but hitherto unobserved experimentally, driven by a normal stress jump across the interface between the bands.
authors.affiliation: Laboratoire Microfluidique, MEMS et Nanostructures, UMR Gulliver CNRS-ESPCI 7083, France.
authors.forename: P
authors.initials: P
authors.lastname: Nghe
authors.forename: S M
authors.initials: SM
authors.lastname: Fielding
authors.forename: P
authors.initials: P
authors.lastname: Tabeling
authors.forename: A
authors.initials: A
authors.lastname: Ajdari