Abstract The effects of radius ratio on fully-developed turbulent concentric annular pipe flow and structures are investigated using direct numerical simulations (DNS). In order to study the radius ratio effects on the flow, four radius ratios of a concentric annular pipe (for R i ∕ R o = 0 . 1 –0.7) are compared at a fixed Reynolds number. Here, R i and R o are the radii of the inner and outer pipes, respectively. It is observed that the radius ratio influences the interaction of two boundary layers developed over the inner and outer cylinder surfaces, and has a significant impact on the turbulent flow structures and dynamics. The characteristics of the flow field are investigated in both physical and spectral spaces, which include the analyses of the first- and second-order statistical moments, budget balance of the transport equation of Reynolds shear stress, two-point correlation coefficients, and premultiplied spectra of velocity and vorticity fluctuations.

中文翻译：

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半径比对湍流同心环状管流及结构的影响

摘要 使用直接数值模拟 (DNS) 研究了半径比对完全发展的湍流同心环形管流和结构的影响。为了研究半径比对流动的影响，在固定雷诺数下比较了同心环形管的四个半径比（对于 R i ∕ R o = 0 . 1 –0.7）。这里，R i 和R o 分别是内管和外管的半径。观察到半径比影响在内外圆柱表面上形成的两个边界层的相互作用，并对湍流结构和动力学产生显着影响。在物理和光谱空间中研究流场的特性，其中包括一阶和二阶统计矩的分析，