AN EXPERIMENTAL INVESTIGATION OF THE VISCOUS SUBLAYER IN TURBULENT PIPE FLOW,

The boundary layer research facility utilizing glycerine with its high viscosity was constructed to permit detailed experimental investigation of the viscous sublayer. In this facility at a pipe Reynolds number of 8700 the sublayer thickness was 0.110 in. which is sufficiently thick to allow detailed investigation in a region that occupies the innermost few thousandths of an inch in most typical air and water flows. Detailed measurements of the streamwise fluctuating velocities with hot-film anemometers were obtained within the viscous sublayer as well as in the transition region between the linear and logarithmic mean velocity profiles. These data were used to form the space-time correlation function of the streamwise fluctuating velocities. From these data an eigen-function expansion of the streamwise fluctuating velocity was obtained which was used to infer the dominant large scale structure of the flow in the wall region. Author