The structure and dynamics of the large-scale circulation in turbulent Rayleigh—Benard convection in a cubic cell are experimentally investigated for fluids with moderate and high Prandtl numbers (from 3.5 to 64). The decomposition of two-dimensional velocity fields into Fourier modes shows that with variation of the Prandtl number from 3.5 to 24 one large-scale mode predominates in the flow. With further increase in the Prandtl number the flow structure considerably changes and the energy is redistributed between several lower Fourier modes. The temporal dynamics of the predominant mode is also considerably changed.

中文翻译：

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高普朗特数湍流对流中大规模环流的结构和动力学

针对中等和高普朗特数（从 3.5 到 64）的流体，实验研究了立方体中湍流瑞利-贝纳德对流中大规模环流的结构和动力学。二维速度场分解为傅立叶模式表明，随着普朗特数从 3.5 到 24 的变化，一种大尺度模式在流动中占主导地位。随着普朗特数的进一步增加，流动结构发生显着变化，能量在几个较低的傅立叶模式之间重新分配。主要模式的时间动态也发生了相当大的变化。