Recent work with the Princeton superpipe by Zagarola & Smits (JFM 1998, vol. 373, p.33) using pitot tubes has shown that the Karman constant is 0.436 and the smooth wall constant is 6.15 while the experiments of Osterlund, et al. (Phys Fluids 2000, Vol.12, p.1) using hot-wires have shown that these constants are 3.8 and 4.1. Work done at Melbourne University by Jones, Marusic and Perry (JFM 2001, vol.468, p.1), show that mean velocity profiles measured using pitot tubes disagreed with profiles measured using hot-wires. The standard MacMillan correction for probe displacement effects and a correction for turbulence intensity were required for obtaining agreement between the two sets of mean velocity profiles. This has motivated us to re-analyze the superpipe data and to carry out mean velocity measurements in a pipe and in a high Reynolds number boundary layer wind tunnel. Results from these experiments and the use of a curvefit by Nickels (2001, 14AFMC) for mean velocity profiles in turbulent wall bounded flow will be discussed.
Min Chong is Reader and Associate Professor at the Mechanical and Manufacturing Engineering Department, University of Melbourne, Australia. His work includes flow visualization, study of coherent structures in coflowing jets and wakes, critical point theory, modeling of wall turbulence using attached eddies and the use of the in variants of the velocity gradient tensor to study the topology of fine scale motions in turbulence. He is at present on study leave at Cambridge University and University of Minnesota.