title: A note on the relationship between turbulent coherent structures and phase correlation.
abstract: Various definitions of coherent structures exist in turbulence research, but a common assumption is that coherent structures have correlated spectral phases. As a result, randomization of phases is believed, generally, to remove coherent structures from the measured data. Here, we reexamine these assumptions using atmospheric turbulence measurements. Small-scale coherent structures are detected in the usual way using the wavelet transform. A considerable percentage of the detected structures are not phase correlated, although some of them are clearly organized in space and time. At larger scales, structures have even higher degree of spatiotemporal coherence but are also associated with weak phase correlation. A series of specific examples are shown to demonstrate this. These results warn about the vague terminology and assumptions around coherent structures, particularly for complex real-world turbulence.
authors.affiliation: School of Mathematical Sciences, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Kang
authors.affiliation: School of Mathematical Sciences, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Danijel
authors.initials: D
authors.lastname: Belušić
authors.affiliation: School of Mathematical Sciences, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Smith-Miles