Scaling of the ‘‘bursting’’ period in turbulent boundary layer and duct flows

Measurements have been made in fully developed turbulent duct and boundary layer flows of the average bursting period over a one decade variation in Reynolds number. The bursting period was determined by two methods: the variable interval time averaging scheme in the form used by Blackwelder and Haritonidis [J. Fluid Mech. 132, 87 (1983)] and the modified u-level scheme of Luchik and Tiederman [J. Fluid Mech. 174, 529 (1987)] in which ejections from the same burst are grouped. All these authors concluded that the bursting period scaled on inner variables. The present results indicate that this conclusion is valid only over a relatively small Reynolds number range, in which low Reynolds number effects are known to be important. At higher Reynolds numbers, scaling on mixed variables provides the best agreement with the data although scaling on outer variables cannot be ruled out.