期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：14
页码：7594-7598
DOI：10.1073/pnas.1922794117
出版社：The National Academy of Sciences of the United States of America
摘要：The global transport of heat and momentum in turbulent convection is constrained by thin thermal and viscous boundary layers at the heated and cooled boundaries of the system. This bottleneck is thought to be lifted once the boundary layers themselves become fully turbulent at very high values of the Rayleigh number R a —the dimensionless parameter that describes the vigor of convective turbulence. Laboratory experiments in cylindrical cells for R a ≳ 1 0 12 have reported different outcomes on the putative heat transport law. Here we show, by direct numerical simulations of three-dimensional turbulent Rayleigh–Bénard convection flows in a slender cylindrical cell of aspect ratio 1 / 10 , that the Nusselt number—the dimensionless measure of heat transport—follows the classical power law of N u = ( 0.0525 ± 0.006 ) × R a 0.331 ± 0.002 up to R a = 1 0 15 . Intermittent fluctuations in the wall stress, a blueprint of turbulence in the vicinity of the boundaries, manifest at all R a considered here, increasing with increasing R a , and suggest that an abrupt transition of the boundary layer to turbulence does not take place.
关键词：turbulent convection ; direct numerical simulation ; turbulent heat transfer
