title: Heat transport in the geostrophic regime of rotating Rayleigh-Bénard convection.
abstract: We report experimental measurements of heat transport in rotating Rayleigh-Bénard convection in a cylindrical convection cell with an aspect ratio of Γ=1/2. The fluid is helium gas with a Prandtl number Pr=0.7. The range of control parameters for Rayleigh numbers 4×10^{9}<Ra<4×10^{11} and for Ekman numbers 2×10^{-7}<Ek<3×10^{-5} (corresponding to Taylor numbers 4×10^{9}<Ta<1×10^{14} and convective Rossby numbers 0.07<Ro<5). We determine the transition from weakly rotating turbulent convection to rotation dominated geostrophic convection through experimental measurements of the heat transport Nu. The heat transport, best collapsed using a parameter RaEk^{β} with 1.65<β<1.8, defines two boundaries in the phase diagram of Ra/Ra_{c} versus Ek and elucidates properties of the geostrophic turbulence regime of rotating thermal convection. We find Nu∼(Ra/Ra_{c})^{γ} with γ≈1 from direct measurement and 1.2<γ<1.6 inferred from scaling arguments.
authors.affiliation: Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ecke
authors.affiliation: International Centre for Theoretical Physics, Strada Costiera 11, 34014 Trieste, Italy.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Niemela