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arXiv 1202.1048physics.flu-dyn
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决定turbulence中平均能量耗散率的大尺度长度

Large-scale length that determines the mean rate of energy dissipation in turbulence

H. Mouri, A. Hori, Y. Kawashima, K. Hashimoto

摘要:

湍流中的平均能量耗散率传统上被假定为与包含能量的大尺度参数成比例,即,纵向速度u的均方根起伏及其相关长度L(u)。然而,所得的比例系数C(u)已知取决于流的大尺度配置。定义了局域能量u2的相关长度L(u2),用几种流动的实验数据研究了标度系数C(u2),发现了C(u2)不依赖于流动构型的可能性.不是L(u)而是L(u2)可以与含能量涡旋的典型尺寸成比例,因此L(u2)确定能量从这些涡旋转移到较小涡旋并最终耗散成热的平均速率。如果用L(u2)对尺度进行归一化,则两点相关性等也与流动构型无关。

英文摘要:

The mean rate of energy dissipation in turbulence is traditionally assumed to scale with parameters of the energy-containing large scales, i.e., the root-mean-square fluctuation of the longitudinal velocity u and its correlation length L(u). However, the resultant scaling coefficient C(u) is known to depend on the large-scale configuration of the flow. We define the correlation length L(u2) of the local energy u2, study the scaling coefficient C(u2) with experimental data of several flows, and find a possibility that C(u2) does not depend on the flow configuration. Not L(u) but rather L(u2) could scale with the typical size of the energy-containing eddies, so that L(u2) determines the mean rate at which the energy is transferred from those eddies to the smaller eddies and is eventually dissipated into heat. The independence from the flow configuration is also found for the two-point correlations and so on if L(u2) is used to normalize the scale.

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