title: Tomographic study of helical modes in bifurcating Taylor-Couette-Poiseuille flow using magnetic resonance imaging.
abstract: The quantitative visualization of flow in a wide-gap annulus (radius ratio 0.5) between concentric cylinders with the inner cylinder rotating and a superimposed axial flow reveals a novel mixed-mode state at relatively high flow rates. A fast magnetic resonance imaging sequence allows the cinematographic dissection and three-dimensional reconstruction of supercritical nonaxisymmetric modes in a regime where stationary helical and propagating toroidal vortices coexist. The findings shed light on symmetry-breaking instabilities, flow pattern selection, and their consequences for hydrodynamic mixing in a complex laminar flow that constitutes a celebrated prototype of many mixing or fractionation processes.
authors.affiliation: Department of Mechanical & Industrial Engineering, Bioengineering Program, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Moser
authors.forename: L G
authors.initials: LG
authors.lastname: Raguin
authors.forename: J G
authors.initials: JG
authors.lastname: Georgiadis