Turbulence structure in a boundary layer with two-dimensional roughness

• DOI: 10.1017/s0022112009007617
• Publication Date: 2009-09-10T10:39:01Z
• Authors: R. J. VOLINO; M. P. SCHULTZ; K. A. FLACK
• Keywords: Reynolds stress

Turbulence measurements for a zero pressure gradient boundary layer over two-dimensional roughness are presented and compared to previous results smooth wall three-dimensional (Volino, Schultz & Flack, J. Fluid Mech ., vol. 592, 2007, p. 263). The present experiments were made on transverse square bars in the fully rough flow regime. turbulence structure was documented through fluctuating velocity components, two-point correlations of swirl strength linear stochastic estimation conditioned Reynolds shear stress. lead significant changes outer flow. stresses, particularly $\overline {{v'}^2} ^ +$ $ - \overline {{u}'{v}'} + , increase, although mean is not as significantly affected. Large-scale turbulent motions originating at increased spatial scales dominant feature flow, however, remains hairpin vortex packets which have similar inclination angles all conditions. differences between layers attributable motion induced by each type roughness. This study has shown produces order height k while generated may be much larger due width elements. It also noted that there fundamental response internal external flows strong perturbations, with being less sensitive effects.