Mean Streamwise Spacing of Organized Structures in Transitional and Developed Bounded Turbulent Flows

The mean periods of passage of organized structures detected by a wide variety of criteria in all regions of turbulent boundary layers, pipes, and channel flows over a range of two Reynolds number decades are compared to that of the transition 'spike'. When scaled with the local mean velocities and the shear layer thicknesses to form a nondimensional streamwise spacing, they fall within a fairly narrow range of TU/delta = 1.5-3.5. The streamwise spacing shows little variation across most of the shear layer for any particular data set.