1999 年 47 巻 546 号 p. 285-290
To investigate the unsteady structure of secondary flow of a turbulent bounded jet in both frequency and physical spaces, the wavelet auto-correlation analysis was used to analyze the fluctuating velocities at various positions in abounded jet. The wavelet auto-correlation analysis provides the auto-correlation characteristics of signals in terms of period and time delay. From the wavelet auto-correlation analysis, the branching structures in WR(a, τ) reveal that a periodic large eddy motion contains the periodic small eddy motions. In the shear layer near the wall at X/b0=8.0, Y/b0 =1.0 and Z/b0=1.9, the wavelet auto-correlation analysis may determine the period and the location of the large-scale structure and the secondary flows.