title: Logarithmic boundary layers in strong Taylor-Couette turbulence.
abstract: We provide direct measurements of the boundary layer properties in highly turbulent Taylor-Couette flow up to Re=2×106) (Ta=6.2×10(12)) using high-resolution particle image velocimetry and particle tracking velocimetry. We find that the mean azimuthal velocity profile at the inner and outer cylinder can be fitted by the von Kármán log law u+=1/κ lny+ +B. The von Kármán constant κ is found to depend on the driving strength Ta and for large Ta asymptotically approaches κ≈0.40. The variance profiles of the local azimuthal velocity have a universal peak around y+≈12 and collapse when rescaled with the driving velocity (and not with the friction velocity), displaying a log dependence of y+ as also found for channel and pipe flows.
authors.affiliation: Department of Applied Physics and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Sander G
authors.initials: SG
authors.lastname: Huisman
authors.forename: Sven
authors.initials: S
authors.lastname: Scharnowski
authors.forename: Christian
authors.initials: C
authors.lastname: Cierpka
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Kähler
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse
authors.forename: Chao
authors.initials: C
authors.lastname: Sun