The turbulent boundary layer on a rough permeable surface

Experimental data on the turbulent boundary layer formed on a rough permeable surface given in a main flow velocity (approximately 20 m/sec), three injection ratios (0.0052, 0.078, and 0.0157), and three intensities of external flow turbulence (approximately 0.3%, 4%, and 11%) are discussed. Distributions are plotted of the mean velocity and turbulence in the boundary layer on a permeable rough surface as measured with a hot-wire anemometer. Densely packed spheres (radius, 2.5 mm) serve as roughness elements. A comparison of the results with similar results for a smooth permeable surface indicates that the effects of roughness and external turbulence decrease with an increase in blowing ratio.