title: Torque scaling in turbulent Taylor-Couette flow with co- and counterrotating cylinders.
abstract: We analyze the global transport properties of turbulent Taylor-Couette flow in the strongly turbulent regime for independently rotating outer and inner cylinders, reaching Reynolds numbers of the inner and outer cylinders of Re(i) = 2×10(6) and Re(o) = ±1.4×10(6), respectively. For all Re(i), Re(o), the dimensionless torque G scales as a function of the Taylor number Ta (which is proportional to the square of the difference between the angular velocities of the inner and outer cylinders) with a universal effective scaling law G ∝ Ta(0.88), corresponding to Nu(ω) ∝ Ta(0.38) for the Nusselt number characterizing the angular velocity transport between the inner and outer cylinders. The exponent 0.38 corresponds to the ultimate regime scaling for the analogous Rayleigh-Bénard system. The transport is most efficient for the counterrotating case along the diagonal in phase space with ω(o) ≈ -0.4ω(i).
authors.affiliation: Physics of Fluids Group, Faculty of Science and Technology, Impact and Mesa Institutes & Burgers Center for Fluid Dynamics, University of Twente, 7500AE Enschede, The Netherlands.
authors.forename: Dennis P M
authors.initials: DP
authors.lastname: van Gils
authors.forename: Sander G
authors.initials: SG
authors.lastname: Huisman
authors.forename: Gert-Wim
authors.initials: GW
authors.lastname: Bruggert
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse