Lagrangian measurement of fluid-particle motion in an isotropic turbulent field
Lagrangian measurement of fluid-particle motion in an isotropic turbulent field
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各向同性湍流场中流体-质点运动的拉格朗日测量
DOI：
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发表时间：
1987
影响因子：
3.7
通讯作者：
Kazuo Yamamoto
中科院分区：
文献类型：
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作者：
Yukinari Sato;Kazuo Yamamoto
通过光学示踪粒子跟踪方法，测量了湍流的拉格朗日特征，包括来自点源的横向扩散的均方值。求出了网格后近似各向同性湍流中的脉动速度v‘值、速度自相关系数RL(τ)和积分尺度ΛL。将这些拉格朗日数据与欧拉积分尺度Λf和双速度相关系数f(R)进行比较，得到以下结果：(I)对于Reλ=20−70的中等湍流雷诺数范围，β(=ΛL/Λf)在0.6-0.3之间，随着Reλ的增加而减小；(Ii)RL与时滞τ的分布类似于f对βr/v‘的分布。此外，理论分析和实验都证实，湍流能量的衰减减弱了$overline{Y^2}(T)$的增长，尤其是在长扩散时间时。
By means of an optical tracer-particle tracking method, measurements for Lagrangian characteristics of turbulence, including the mean-square value of lateral diffusion from a point source $overline{Y^2}$, the r.m.s. value of fluctuating velocity v′, the velocity autocorrelation coefficient RL(τ), and the integral scale ΛL, were made in approximately isotropic turbulent flow behind a grid. Comparison of these Lagrangian data with the Eulerian integral scale Λf and the double velocity correlation coefficient f(r) led to the following results: (i) for a moderate turbulent Reynolds-number range of Reλ = 20 − 70, the ratio β(= ΛL/Λf) is within the values of 0.6 – 0.3, becoming lower as Reλ increases, and (ii) the distribution of RL against time lag τ is analogous to that of f against βr/v′. Further, it was confirmed by both theoretical analysis and experiments that the growth of $overline{Y^2}(t)$ was weakened by the decay of turbulent energy, particularly so for long diffusion times.