POD and Wavelet Analysis of Coherent Structures in a Turbulent Mixing Layer.
Hitoshi Ishikawa, Masaru KIYA, Osamu MOCHIZUKI, Hiroshi Maekawa · TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B · 1997
Coherent structures in a turbulent plane mixing layer are comparatively studied by wavelet transform and proper orthogonal decomposition (POD) analysis, using the database of the mixing layer obtained by Bonnet et al. (1994). The POD analysis yields more coherent vorticity distributions of the large-scale structures in the mixing layer, suggesting that the first mode represents the most dominant structure. The wavelet transform indicates the low-frequency modulation of vorticity of the large-scale structure. The POD analysis fails to show the large-scale structure in the central part of the mixing layer due to the effects of the random components, whereas the wavelet transform can extract the coherent structure if the vortex-passage period is chosen as the scale of the wavelet.