Comment on the scaling of the near-wall streamwise variance peak in turbulent pipe flows

Authors: Örlü, R., Alfredsson, P.H.
Document Type: Article
Pubstate: Published
Journal: Exp. Fluids
Volume: 54   1431
Year: 2012


Apparent contradictory results regarding the Reynolds number (Re) scaling of the near-wall peak of the streamwise velocity variance distribution in turbulent pipe flows (Ng et al. Exp Fluids 51, 1261 and Vallikivi et al. Exp. Fluids 51, 1521) are discussed. Conclusions from the Princeton University/ONR Superpipe published between 2010 and 2012 are examined, doubts are raised, and recent numerical and experimental results are supplemented. The compiled results support the view that the inner-scaled peak amplitude increases with Re (at least to a Kármán number (R+) of 3,000) in contrast to the view put forward by several publications based on results from the Superpipe. Consequently, there is a need for further experimental results for R+>3,000 to ascertain the trend at higher Re.