Laterally converging duct flows. Part 3. Mean turbulence structure in the viscous layer
Laterally converging duct flows. Part 3. Mean turbulence structure in the viscous layer
复制标题
横向会聚的管道流。
DOI：
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发表时间：
2006
影响因子：
3.7
通讯作者：
H. Eckelmann
中科院分区：
文献类型：
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作者：
D. McEligot;H. Eckelmann
为了为将有利的流向压力梯度效应纳入内部湍流和湍流边界层模型提供基本依据，我们在一个油槽中同时使用交叉导线探头和壁面剪切应力传感器对完全发育和横向收敛的流动进行了时间序列测量。数据集中在粘性层和中心面上，以轻微到高度有利的压力梯度。（这里粘性层被定义为粘性效应显著的区域，但不一定占主导地位；在一些研究人员的术语中，它包括“层流”和缓冲子层）。结果包括流向分量和墙向分量及其乘积和墙剪应力的平均统计量、相关性和谱的分布的比较。关键的新数据是测量的波动法向分量和相关统计在粘性层的高度有利的压力梯度。对于粘性层的外半部，其均方根波动随着压力梯度的增加而减小，这与迄今为止未经证实的直接数值模拟预测一致。根据对概率密度分布的考察，可以得出这样的结论：强压力梯度的作用是减少粘性层外层动量的输运。
In order to provide fundamental bases for incorporating the effects of favourable streamwise pressure gradients into models for internal turbulent flows and turbulent boundary layers, time series measurements with a cross-wire probe and a wall shear stress sensor were obtained simultaneously in an oil channel both for fully developed and laterally converging flows. Data were concentrated in the viscous layer and at the centreplane for slight to highly favourable pressure gradients. (Here the viscous layer is defined as the region where viscous effects are significant, but not necessarily dominant; it includes the ‘laminar’ and buffer sublayers in the terminology of some investigators). Results presented include comparisons of the profiles of the mean statistics, plus correlations and spectra, of streamwise and wall-normal components, their product and the wall shear stress. The key new data are the measurements of the fluctuating normal component and related statistics in the viscous layer for highly favourable pressure gradients. For the outer half of the viscous layer its root-mean-square fluctuations decrease as the pressure gradient is increased, consistent with heretofore unconfirmed predictions from direct numerical simulations. Based on examination of the probability density distributions, one may conclude that an effect of a strong pressure gradient is to reduce transport of momentum in the outer part of the viscous layer.