title: Dynamical role of slip heterogeneities in confined flows.
abstract: We demonstrate that flows in confined systems are controlled by slip heterogeneities below a certain size. To show this we image the motion of soft glassy suspensions in microchannels whose inner walls impose different slip velocities. As the channel height decreases, the flow ceases to have the symmetric shape expected for yield-stress fluids. A theoretical model accounts for the role of slip heterogeneities and captures the velocity profiles. We generalize these results by introducing a length scale, valid for all fluids, below which slip heterogeneities dominate the flow in confined systems. General implications of this notion, concerning the interplay between slip and confinement, are presented.
authors.affiliation: Laboratoire Microfluidique, MEMs et Nanostructures, ESPCI ParisTech, UMR Gulliver 7083, ESPCI, CNRS, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Vayssade
authors.affiliation: Laboratoire Microfluidique, MEMs et Nanostructures, ESPCI ParisTech, UMR Gulliver 7083, ESPCI, CNRS, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Choongyeop
authors.initials: C
authors.lastname: Lee
authors.affiliation: Laboratoire Microfluidique, MEMs et Nanostructures, ESPCI ParisTech, UMR Gulliver 7083, ESPCI, CNRS, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Terriac
authors.affiliation: Laboratoire Microfluidique, MEMs et Nanostructures, ESPCI ParisTech, UMR Gulliver 7083, ESPCI, CNRS, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Monti
authors.affiliation: Matière Molle et Chimie, UMR 7167 CNRS - ESPCI ParisTech, ESPCI, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Cloitre
authors.affiliation: Laboratoire Microfluidique, MEMs et Nanostructures, ESPCI ParisTech, UMR Gulliver 7083, ESPCI, CNRS, 10 Rue Vauquelin, 75005 Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tabeling