National Repository of Grey Literature 2 records found  Search took 0.02 seconds. 
Assessing Quality of Boundary Layer Flows With the Diagnostic Plot
Jurčáková, Klára ; Procházka, Pavel P. ; Kellnerová, Radka
We experimentally investigated turbulent boundary layers over 4 rough surfaces and 1 smooth surface by particle image velocimetry for a range a free stream velocities. The obtained mean velocity vertical profiles were universally scaled by roughness length z₀ and friction velocity u*, but both parameters have to be obtained from the fit of the logarithmic or composite velocity pro le to the experimental data. Diagnostic plot, which relates turbulence intensity with the mean velocity showed good collapse of different free stream velocities for each surface. It became fully universal in its modified version when the roughness function was taken into an account. We found that turbulence intensities over our surfaces are higher than any published one and that they dependent on roughness length z₀*.
Generating a very rough turbulent boundary layer in wind tunnel Wotan, Meteorological Institute, Hamburg
Kellnerová, Radka ; Jaňour, Zbyněk
Contribution poses flow characteristics of symmetric very rough turbulent layer in wind-tunnel Wotan in Hamburg. Measurement was conducted using 2-D component LDA with high temporal resolution. Requirements for generating a top quality boundary layer with consistent parameters that follow up-to-date science of physical modeling are described and explained. Main attention was focused on linkage between integral length scale and turbulence intensity Ix and Iz according to guideline VDI.

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