Turbulent boundary layer measurements were made on a flat plate covered with uniform spheres and also on the same surface with the addition of a finer-scale ...
Experiments in Fluids (2005) 38: 328–340 DOI 10.1007/s00348-004-0903-2
O R I GI N A L S
M. P. Schultz Æ K. A. Flack
Outer layer similarity in fully rough turbulent boundary layers
Received: 19 March 2004 / Revised: 15 October 2004 / Accepted: 15 October 2004 / Published online: 18 February 2005 Springer-Verlag 2005
Abstract Turbulent boundary layer measurements were made on a flat plate covered with uniform spheres and also on the same surface with the addition of a finerscale grit roughness. The measurements were carried out in a closed return water tunnel, over a momentum thickness Reynolds number (Reh) range of 3,000–15,000, using a two-component, laser Doppler velocimeter (LDV). The results show that the mean profiles for all the surfaces collapse well in velocity defect form. Using the maximum peak to trough height (Rt) as the roughness length scale (k), the roughness functions (DU+) for both surfaces collapse, indicating that roughness texture has no effect on DU+. The Reynolds stresses for the two rough surfaces also show good agreement throughout the entire boundary layer and collapse with smooth wall results outside of the roughness sublayer. Quadrant analysis and the velocity triple products show changes in the rough wall boundary layers that are confined to y
