DOI: 10.1615/TSFP5
COHERENT STRUCTURES AND HEAT TRANSPORT IN TURBULENT RAYLEIGH-BENARD CONVECTION
ABSTRAKT
Thermal plumes and their role for the heat transport in turbulent Rayleigh−Bénard convection of air (Prandtl number Pr = 0.7) in a cylindrical cell are investigated analysing data obtained from Direct Numerical Simulations (DNS) and well-resolved Large-Eddy Simulations (LES). DNS have been performed for the Rayleigh numbers Ra = 106 and 107 and aspect ratio of a cylindrical container Γ = 5 and LES for Ra = 108 and Γ = 5. Additionally a LES has been conducted for Ra = 109 and Γ = 1 to provide a high Rayleigh number flow field for a parametrized plume analysis. It is shown that the number of the thermal plumes increase with increasing Rayleigh numbers while their size decreases. Further, temperature thresholds are determined based on a thermal dissipation rate analysis, which are used for plume extraction.