A wavelet pattern recognition technique for identifying flow structures in cylinder generated wakes

A pattern recognition technique, applied in wavelet space, with enhanced capabilities of identifying multiple flow templates based on scale is introduced and applied to the turbulent, intermediate wake region of a circular cylinder. The advantage of this enhanced pattern recognition technique is two-folded: (i) the wavelet templates can be easily identified based on the sharp definition of modulus maxima lines and (ii) the scale separation in wavelet space allows for the identification of multiple structures. This new technique is used to investigate the relationship between the primary (spanwise) and secondary (streamwise) wake structures. The analysis relates the interactions between these two flow structures to a local loss of periodicity in the Karman vortex street.