Statistical properties of the local structure of homogeneous isotropic turbulence and turbulent channel flows
Statistical properties of the local structure of homogeneous isotropic turbulence and turbulent channel flows
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均匀各向同性湍流和湍流通道流局部结构的统计特性
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
T. Miyauchi
中科院分区：
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作者：
Hiromichi Kobayashi;E. Matsumoto;N. Fukushima;M. Tanahashi;T. Miyauchi
利用Reλ=60.1∼287.6的均匀各向同性湍流和Reτ=1 80、4 0 0、80 0和12 70的槽道湍流的直接数值模拟数据，研究了局部结构的统计特性。无因次第二不变量被用作代表性的局部结构，并且被定义为速度梯度张量的第二不变量，该第二不变量被速度梯度张量的大小归一化。在均匀各向同性湍流中，对于不同的雷诺数，无量纲第二不变量的概率密度函数(Pdf)分布具有很好的一致性。当雷诺数较高时，无因次第二不变量的体积分数、平均值和方差分别收敛到某一值。对于槽道湍流，不同雷诺数下的无量纲次不变量的pdf分布对于壁面单位距壁面的距离有很好的重合。通道中心的无量纲次不变量的概率密度和体积分数与均匀各向同性湍流的概率密度和体积分数符合得很好。
Statistical properties of the local structure are investigated using the data of direct numerical simulation of homogeneous isotropic turbulence for Re λ=60.1∼287.6 and turbulent channel flows for Re τ = 180, 400, 800, and 1270. The dimensionless second invariant is used as the representative local structure, and is defined as the second invariant of a velocity gradient tensor normalized by the magnitude of the velocity gradient tensor. In homogeneous isotropic turbulence, the probability density function (pdf) profiles of the dimensionless second invariant show good agreement for different values of Reynolds number. The volume fraction, the average, and the variance of the dimensionless second invariant converge to certain values at high Reynolds number, respectively. For the turbulent channel flows, the pdf profiles of the dimensionless second invariant for different values of Reynolds number coincide very well for the distance from the wall in wall units. The probability density and the volume fraction of the dimensionless second invariant at the center of the channel are in good agreement with those of homogeneous isotropic turbulence.