Spatio-temporal intermittency of the turbulent energy cascade
Spatio-temporal intermittency of the turbulent energy cascade
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DOI：
10.1017/jfm.2018.584
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发表时间：
2017-11
影响因子：
3.7
通讯作者：
T. Yasuda;J. C. Vassilicos
中科院分区：
文献类型：
--
作者：
T. Yasuda;J. C. Vassilicos
在不可压缩的周期统计定常湍流中，湍流能量在尺度和空间上的交换表现为时间导数项、脉动能量的空间湍流输运和压力-速度项在零点附近非常强烈的间歇性时空涨落。这些波动相互关联，并与尺度间能量转移率的剧烈间歇性波动相关。这种关联是由扫掠效应、非线性和非局部性的联系引起的，在尺度间传递率和压力-速度项关联的情况下，还与两点脉动压力差和两点脉动速度差之间的几何对齐有关。在统计平稳和均匀的湍流中，所有这些过程都不存在于湍流叶栅的时空平均图像中。
In incompressible and periodic statistically stationary turbulence, exchanges of turbulent energy across scales and space are characterised by very intense and intermittent spatio-temporal fluctuations around zero of the time-derivative term, the spatial turbulent transport of fluctuating energy and the pressure–velocity term. These fluctuations are correlated with each other and with the intense intermittent fluctuations of the interscale energy transfer rate. These correlations are caused by the sweeping effect, the link between nonlinearity and non-locality, and also relate to geometrical alignments between the two-point fluctuating pressure force difference and the two-point fluctuating velocity difference in the case of the correlation between the interscale transfer rate and the pressure–velocity term. All these processes are absent from the spatio-temporal-average picture of the turbulence cascade in statistically stationary and homogeneous turbulence.