Characteristics of single and clusters of bursting events in the inner region of a turbulent channel flow
Résumé
The grouping method we developed in earlier work is applied to the ejections identified by level crossings of the $u′v′$ signal in the inner layer of a fully developed turbulent channel flow. The groups of ejections and solitary events are separately investigated. Their frequencies, contributions to the mean $\overline{u′v′}$ and related conditional averages are reported. It is argued that the packets and single events result from different regeneration mechanisms. The coherent streamwise alignment of the structures within the groups makes the associated scale significantly large. The groups transport large values of the kinetic energy and of the Reynolds shear stress. The results confirm recent studies and show that the main features of the near-wall turbulence dynamics can be adequately revealed by single-point measurements.
