Detecting Multi-Scale Coherent Eddy Structures and Intermittency in Turbulent Boundary Layer by Wavelet Analysis
Detecting Multi-Scale Coherent Eddy Structures and Intermittency in Turbulent Boundary Layer by Wavelet Analysis
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DOI：
10.1088/0256-307x/22/8/041
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发表时间：
2005-08
影响因子：
3.5
通讯作者：
J. Nan;Zhang Jin
中科院分区：
文献类型：
--
作者：
J. Nan;Zhang Jin
对湍流边界层流动的精细测量所获得的速度时间序列进行了小波变换多尺度分解。通过利用小波系数的多尺度瞬时强度因子和平坦度因子，提出了一种用于检测湍流场中多尺度相干涡结构的条件采样技术。尽管湍流边界层中相干涡结构的数量很少，但它们相对于湍流动能的能量百分比却很高。特别是在缓冲层中，相干结构的能量百分比明显高于对数层中的能量百分比，这表明缓冲层是湍流边界层中最活跃的区域。这些多尺度相干涡结构具有一些共同的动力学特征，并对湍流边界层中的反常标度律负责。
Multi-scale decomposition by wavelet transform has been performed to velocity time sequences obtained by fine measurements of turbulent boundary layer flow. A conditional sampling technique for detecting multi-scale coherent eddy structures in turbulent field is proposed by using multi-scale instantaneous intensity factor and flatness factor of wavelet coefficients. Although the number of coherent eddy structures in the turbulent boundary layer is very small, their energy percentage with respect to the turbulence kinetic energy is high. Especially in buffer layer, the energy percentages of coherent structures are significantly higher than those in the logarithmic layer, indicating that the buffer layer is the most active region in the turbulent boundary layer. These multi-scale coherent eddy structures share some common dynamical characteristics and are responsible for the anomalous scaling law in the turbulent boundary layer.