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Detecting Multi-Scale Coherent Eddy Structures and Intermittency in Turbulent Boundary Layer by Wavelet Analysis |
| JIANG Nan;ZHANG Jin |
| Department of Mechanics, Tianjin University, Tianjin 300072 |
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| Cite this article: |
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JIANG Nan, ZHANG Jin 2005 Chin. Phys. Lett. 22 1968-1971 |
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Abstract 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.
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| Keywords:
47.27.Lx
47.27.Nz
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Published: 01 August 2005
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