Heat transport in turbulent Rayleigh - Bénard convection for Pr ≃ 0 . 8 and Ra ≲ 1015
نویسندگان
چکیده
We report experimental results for the heat transport, as expressed by the Nusselt number Nu, by turbulent Rayleigh-Bénard convection in a cylindrical sample of aspect ratio Γ ≡ D/L = 0.50 (D = 1.12 m is the diameter and L = 2.24 m the height). The measurements are for the Rayleigh-number range 10 <∼ Ra <∼ 10 15 and for a Prandtl number Pr ' 0.86. At these large Ra the results were exceptionally sensitive to details of the experiment. Near Ra = 10 the Nusselt number could be caused to vary over the range 3500 <∼ Nu <∼ 5800 by minor changes in the apparatus or operating procedure.
منابع مشابه
Heat transport by turbulent Rayleigh–Bénard convection for Pr ≃ 0.8 and 3 × 1012 ≲ Ra ≲ 1015: aspect ratio Γ = 0.50
We report on the experimental results for heat-transport measurements, in the form of the Nusselt number Nu, by turbulent Rayleigh–Bénard convection (RBC) in a cylindrical sample of aspect ratio 0 ≡ D/L = 0.50 (D = 1.12m is the diameter and L = 2.24m the height). The measurements were made using sulfur hexafluoride at pressures up to 19 bar as the fluid. They are for the Rayleigh-number range 3...
متن کاملPrandtl-, Rayleigh-, and Rossby-number dependence of heat transport in turbulent rotating Rayleigh-Bénard convection.
Experimental and numerical data for the heat transfer as a function of the Rayleigh, Prandtl, and Rossby numbers in turbulent rotating Rayleigh-Bénard convection are presented. For relatively small Ra approximately 10(8) and large Pr modest rotation can enhance the heat transfer by up to 30%. At larger Ra there is less heat-transfer enhancement, and at small Pr less, similar 0.7 there is no hea...
متن کاملScaling laws in turbulent Rayleigh-Bénard convection under different geometry
A systematic study of turbulent Rayleigh-Bénard convection is carried out in two horizontal cylindrical cells of different lengths filled with water. Global heat transport and local temperature and velocity measurements are made over varying Rayleigh numbers Ra. The scaling behavior of the measured Nusselt number Nu(Ra) and the Reynolds number Re(Ra) associated with the large-scale circulation ...
متن کاملHeat transport by turbulent Rayleigh–Bénard convection for Pr ≃ 0.8 and 4 × 1011 ≲ Ra ≲ 2 × 1014: ultimate-state transition for aspect ratio Γ = 1.00
We report experimental results for heat-transport measurements, in the form of the Nusselt number Nu, by turbulent Rayleigh–Bénard convection (RBC) in a cylindrical sample of aspect ratio 0 ≡ D/L = 1.00 (D = 1.12m is the diameter and L = 1.12m the height) and compare them with previously reported results for 0 = 0.50. The measurements were made using sulfur hexafluoride at pressures up to 19 ba...
متن کاملHeat transfer and large scale dynamics in turbulent Rayleigh-Bénard convection
The progress in our understanding of several aspects of turbulent Rayleigh-Bénard convection is reviewed. The focus is on the question of how the Nusselt number and the Reynolds number depend on the Rayleigh number Ra and the Prandtl number Pr, and on how the thicknesses of the thermal and the kinetic boundary layers scale with Ra and Pr. Non-Oberbeck-Boussinesq effects and the dynamics of the ...
متن کامل