Wavelet analysis of the near-field structure in a bounded jet

In order to reveal the flow structure of a turbulent bounded jet in both Fo urier and physical spaces, the wavelet cross spectrum function is firstly p roposed based on the wavelet transform in this paper. Then, the wavelet tra nsform, local wavelet Reynolds stress and wavelet Reynolds stress are used to analyze the large eddy motions and the secondary flow structure over a m easured frequency-physical plane. The experimental fluctuating velocities a t various positions in the near-field are used for the analyses. From wavel et Reynolds stress analysis, the frequency and location of the large-scale motion in the shear layer and the secondary flow near the wall can be deter mined. The branching structure of multi-scale eddies in the wall shear laye r becomes more complex than that in the free shear layer. Due to the effect of the secondary flow, the scales of eddy and entrainment process become s mall.