title: Universal and wide shear zones in granular bulk flow.
abstract: We present experiments on slow granular flows in a modified (split-bottomed) Couette geometry in which wide and tunable shear zones are created away from the sidewalls. For increasing layer heights, the zones grow wider (apparently without bound) and evolve towards the inner cylinder according to a simple, particle-independent scaling law. After rescaling, the velocity profiles across the zones fall onto a universal master curve given by an error function. We study the shear zones also inside the material as a function of both their local height and the total layer height.
authors.affiliation: Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands.
authors.forename: Denis
authors.initials: D
authors.lastname: Fenistein
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: van de Meent
authors.forename: Martin
authors.initials: M
authors.lastname: van Hecke