Near-Wall Coherent Structures: History, Identification and Detection - Transport and Coherent Structures in Wall Turbulence - page 138

by Wallace et al. [WAL 77]. The measurements coupled with
visualizations performed by Bogard [BOG 82] and Talmon
et al. [TAL 86] enabled us to clarify the influence of the
different detection parameters. This section presents the
Eulerian detection methods that are most widely used,
essentially by experimenters. Other single-point
identification techniques do exist, but they are generally a
combination of the various techniques presented here. The
window averaged gradient (WAG) technique suggested by
Antonia and Fulachier [ANT 89], for example, is a linearized
version of the “Mexican hat” wavelet [TAR 99, TAR 07].
[SUL 94] combines wavelet analysis with VITA, while [MOR
92] simultaneously detects shear layers and ejections.

The results presented in this section were obtained in
the hydrodynamic channel of LEGI (Laboratoire des
Ecoulements Géophysiques et Industriels, Grenoble, France)
described in [TAR 94] at a Reynolds number . They
coincide well with the results available in the literature at
moderate

Re

τ =

500

numbers.

Re

Figure 3.6. Distribution of the uv events in quadrants