An experimental study of helicity density in turbulent flows
An experimental study of helicity density in turbulent flows
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DOI：
10.1063/1.858371
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发表时间：
1992-09
影响因子：
4.6
通讯作者：
J. Wallace;J. Balint;L. Ong
中科院分区：
文献类型：
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作者：
J. Wallace;J. Balint;L. Ong
对Rθ=2685的湍流边界层、Rθ=5800的湍流双流混合层和RM= 23400的湍流网格流的数据库进行了相对螺旋度密度h=（U <$Ω）/<$U <$<$Ω <$的特性检验。在这些流动中，使用具有几个Kolmogorov微尺度空间分辨率的九个热线传感器的微型探针同时测量速度和涡度矢量U和Ω。这种分析的结果与Rogers和Moin [Phys.Fluids30，2662（1987）]的直接数值槽流模拟的类似分析基本一致。结果并不支持这样的观点：流动在局部很有可能达到类似贝尔特拉米的状态，并且速度和涡度矢量通常几乎对齐。在网格流中不会出现这种优选的排列，而在剪切流区域中只会稍微出现这种情况，在剪切流区域中，已知平均速度与相干涡在某种程度上是一致的。联合概率分析...
Databases for a turbulent boundary layer at Rθ=2685, a turbulent two‐stream mixing layer at Rθ=5800, and a turbulent grid flow at RM=23 400 have been examined for properties of the relative helicity density, h=(U⋅Ω)/‖U‖‖Ω‖. The velocity and vorticity vectors U and Ω were simultaneously measured in these flows using a miniature probe with nine hot‐wire sensors with a spatial resolution of a few Kolmogorov microscales. The results of this analysis are in generally good agreement with a similar analysis of a direct numerical channel flow simulation of Rogers and Moin [Phys. Fluids 30, 2662 (1987)]. The results do not support the suggestion that there is a high probability for the flows locally to achieve a Beltrami‐like state with the velocity and vorticity vectors often nearly aligned. Such preferred alignment does not occur in the grid flow and only slightly occurs in regions of the shear flows where it is known that the mean velocity is somewhat aligned with coherent vortices. A joint probability analysis...