Comment on ''Extended self-similarity in turbulent flows''

A recent paper [R. Benzi et al., Phys. Rev. E 48, R29 (1993)] concluded that the scaling of turbulent structure functions extends deeper into the viscous subrange than what has been assumed so far. We comment on this notion of ''extended selfsimilarity.'' We verify the (approximate) universal character of the viscous subrange scaling of structure functions but show that it is different from their inertial range scaling. The effect is small (although significant) in laboratory flows and it has profound consequences for the multifractal model