A new scaling for the streamwise turbulence intensity in wall-bounded turbulent flows and what it tells us about the "outer" peak

Authors: Alfredsson, P.H., Segalini, A. S., Örlü, R.
Document Type: Article
Pubstate: Published
Journal: Phys. Fluids
Volume: 23   041702
Year: 2011


One recent focus of experimental studies of turbulence in high Reynolds number wall-bounded flows has been the scaling of the root mean square of the fluctuating streamwise velocity, but progress has largely been impaired by spatial resolution effects of hot-wire sensors. For the near-wall peak recent results seem to have clarified the controversy, however, one of the remaining issues in this respect is the emergence of a second (so called outer) peak at high Reynolds numbers. The present Letter introduces a new scaling of the local turbulence intensity profile, based on the diagnostic plot by Alfredsson & Örlü [Eur. J. Fluid Mech. B/Fluids, 42, 403 (2010)], which predicts the location and amplitude of the `outer' peak, and suggests its presence as a question of sufficiently large scale separation.