Large-scale mean patterns in turbulent convection
Large-scale mean patterns in turbulent convection
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DOI：
10.1017/jfm.2015.316
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发表时间：
2015-08-01
影响因子：
3.7
通讯作者：
Schumacher, Joerg
中科院分区：
文献类型：
--
作者：
Emran, Mohammad S.;Schumacher, Joerg
在Rayleigh数Ra < 10（4）的热对流的螺旋缺陷混沌（SDC）状态中众所周知的大尺度模式继续存在于纵横比Gamma = 50和Ra > 10（5）的扩展圆柱形单元中的湍流Rayleigh-Benard对流的三维数值模拟中。当湍流场在时间上被平均，湍流波动被消除时，它们就显现出来了。我们应用Boussinesq封闭估计湍流粘度和扩散系数，分别。由此产生的湍流瑞利数Ra-*，描述对流的平均模式，确实是在SDC范围内。湍流的普朗特数小于1，为0.2
Large-scale patterns, which are well-known from the spiral defect chaos (SDC) regime of thermal convection at Rayleigh numbers Ra < 10(4), continue to exist in three-dimensional numerical simulations of turbulent Rayleigh-Benard convection in extended cylindrical cells with an aspect ratio Gamma = 50 and Ra > 10(5). They are revealed when the turbulent fields are averaged in time and turbulent fluctuations are thus removed. We apply the Boussinesq closure to estimate turbulent viscosities and diffusivities, respectively. The resulting turbulent Rayleigh number Ra-*, that describes the convection of the mean patterns, is indeed in the SDC range. The turbulent Prandtl numbers are smaller than one, with 0.2