Extended self-similarity in boundary layer turbulence

It is shown that a lack of isotropy narrows the range of spatial scales where turbulent flows exhibit extended self-similarity (ESS), namely, self-scaling of velocity structure functions. This effect holds irrespectively of the order of the structure functions and explains why early experiments on turbulent boundary layers failed to observe ESS. The shrinking of the ESS range of scales is well captured by the approximate analytical scaling functions developed by Sreenivasan and co-workers [Phys. Rev. E 48, R33 (1993); 48, 5 (1993); 48, R3217 (1993)] to fit atmospheric boundary layer data.