منابع مشابه
Ultimate state of thermal convection.
The ultimate regime of thermal convection, the so-called Kraichnan regime [R. H. Kraichnan, Phys. Fluids 5, 1374 (1962)]], hitherto has been elusive. Here numerical evidence for that regime is presented by performing simulations of the bulk of turbulence only, eliminating the thermal and kinetic boundary layers and replacing them with periodic boundary conditions.
متن کاملTransition to the ultimate state of turbulent Rayleigh-Bénard convection.
Measurements of the Nusselt number Nu and of a Reynolds number Re(eff) for Rayleigh-Bénard convection (RBC) over the Rayleigh-number range 10(12)≲Ra≲10(15) and for Prandtl numbers Pr near 0.8 are presented. The aspect ratio Γ≡D/L of a cylindrical sample was 0.50. For Ra≲10(13) the data yielded Nu∝Ra(γ(eff)) with γ(eff)≃0.31 and Re(eff)∝Ra(ζ(eff)) with ζ(eff)≃0.43, consistent with classical turb...
متن کاملUltimate-state transition of turbulent Rayleigh-Bénard convection
Guenter Ahlers,1,2,* Eberhard Bodenschatz,2,3,4,* and Xiaozhou He5,* 1Department of Physics, University of California, Santa Barbara, California 93106, USA 2Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany 3Institute for Nonlinear Dynamics, University of Göttingen, 37077 Göttingen, Germany 4Laboratory of Atomic and Solid-State Physics and Sibley School o...
متن کاملSearch for the "ultimate state" in turbulent Rayleigh-Bénard convection.
Measurements of the Nusselt number Nu and of temperature variations DeltaTb in the bulk fluid are reported for turbulent Rayleigh-Bénard convection of a cylindrical sample. They cover the Rayleigh-number range 10(9) less than or similar to Ra less than or similar to 3x10(14) using He (Prandtl number Pr=0.67), N2 (Pr=0.72) and SF6 (Pr=0.79 to 0.84) at pressures up to 15 bars and near-ambient tem...
متن کاملRoughness as a Route to the Ultimate Regime of Thermal Convection.
We use highly resolved numerical simulations to study turbulent Rayleigh-Bénard convection in a cell with sinusoidally rough upper and lower surfaces in two dimensions for Pr=1 and Ra=[4×10^{6},3×10^{9}]. By varying the wavelength λ at a fixed amplitude, we find an optimal wavelength λ_{opt} for which the Nusselt-Rayleigh scaling relation is (Nu-1∝Ra^{0.483}), maximizing the heat flux. This is ...
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ژورنال
عنوان ژورنال: Physical Review Letters
سال: 2003
ISSN: 0031-9007,1079-7114
DOI: 10.1103/physrevlett.90.034502