Wavelet Cross-Correlation Analysis : Analysis of Vortical Structures in a Turbulent Plane Jet

• Published in: Nihon Kikai Gakkai rombunshuu. B hen Vol. 62; no. 597; pp. 1810 - 1818
• Main Authors: LI, Hui, NOZAKI, Tsutomu
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Society of Mechanical Engineers 1996
• Subjects: Fluctuation Velocity
• ISSN: 0387-5016; 1884-8346
• DOI: 10.1299/kikaib.62.1810

A new cross-correlation method, which is called a wavelet cross-correlation analysis and expresses the statistical cross-correlation of any signal in terms of period and time delay, is proposed and its main properties are presented. By analyzing two typical signals, the cross-correlations of components with different periods can be detected, and it is shown that wavelet cross-correlation can overcome the limitations of classical cross-correlation. As a practical application to the field of fluid mechanics, wavelet cross-correlation is employed to analyze cross-correlation relationships between χ-components of the fluctuation velocities at two points on opposite sides of the centerline and along the centerline of a plane turbulent jet in terms of period and time delay. From the distributions of the wavelet cross-correlation coefficient, similar structures of motions with various scales are shown, and the successive branching of vortex structures is observed. The period of vortex and apparent flapping motions can be easily determined in terms of period and time delay.