Near-wall streamwise turbulence intensity as Reτ→∞

Two possible and physically meaningful scalings for near-wall streamwise turbulence intensity are derived using velocity spectra. First, if viscous wall effect on the wall-attached inactive motions from the log and outer layers is negligible enough so that the related spectrum does not diminish with Reynolds number, the near-wall turbulence intensity grows indefinitely and scales as ln Re_. Whereas if it is strong enough so that the near-wall turbulence intensity remains finite at all Reynolds numbers, it scales as 1/ln Re_. The existing measurement data favors the latter scaling, but the issue will be settled by the availability of such data at higher Reynolds numbers.