Response to “Scaling of the intermediate region in wall-bounded turbulence: The power law” [Phys. Fluids 10 , 1043 (1998)]

Abstract

Recent experiments at Princeton have established new scaling laws for the velocity profile in fully developed turbulent pipe flow. The data cover a Reynolds number ranging between 31*10/sup 3/ and 35*10/sup 6/, where the Reynolds number Re is based on mean velocity U and pipe diameter D and they extend the data base for smooth pipe flow over an order of magnitude beyond the highest Reynolds number obtained by Nikuradse (1932). In a number of articles commenting on this work, most notably Barenblatt and Chorin (see ibid., 1998) have stated that they "regretfully concluded that the Princeton data are tainted by roughness starting at Re=10/sup 6/. " We dispute this conclusion and show that, within the error bounds of the data, there are no discernible roughness effects even at a Reynolds number of 35*10/sup 6/. We regret that this unfortunate misunderstanding has arisen, and we apologize for not giving this matter our full attention. Specifically, we apologize for not dealing more fully with the issue of roughness in our previous work (10 Refs.)