An experimental study of the high Reynolds number turbulent boundary layer

The high Reynolds number turbulent boundary layer is analyzed in light of experimental data obtained in the surface layer of the atmospheric boundary layer. The data were obtained at the Surface Layer Turbulence and Environmental Sciences Test facility located on the southern end of the western Utah salt flats. Two component hot-wire anemometry was used to obtain the instantaneous streamwise and wall-normal velocity components in a wall-normal array from 6 mm to 2 m above the surface of the flats. The data were obtained in both "fully" rough and "transitionally" rough boundary layers, and were found to be consistent with Townsend's Reynolds number similarity hypothesis. From these data mean-velocity, broad band-turbulence intensity, and spectral profiles were obtained and used to critique existing similarity formulations. From the results of the analysis the turbulence intensity formulations are extended to be applicable across the entire smooth-wall boundary layer. The new extended formulations are compared to experimental and computational data across a Reynolds number range of four orders of magnitude. The new formulations are founded on the physical arguments of the attached eddy hypothesis, and suggest the boundary layer changes significantly with Reynolds number, with an outer flow influence felt all the way down to the wall.; Another experimental investigation is also presented concerning a study of the wall boundary condition for Large Eddy Simulation (LES) of a turbulent boundary layer. Three conventional boundary conditions are tested a priori using experimental data. This was done using arrays of hot-film sensors and x-probes to measure filtered wall shear stress and streamwise and wall-normal velocities at locations nominally within the log region of the flow. A correction method was also developed to remedy hot-film sensor amplitude attenuation. Along with an analysis of the existing models, a new model is proposed that gives better agreement with the filtered shear stress measured at the wall. The new model is consistent with 'outer-flow' scaling similarity of the streamwise velocity spectra and is therefore expected to be more generally applicable over a larger range of Reynolds numbers at any first-grid position within the log region of the boundary layer.