A turbulent boundary layer over a two-dimensional rough wall (original) (raw)

Particle Image Velocimetry (PIV) measurements and Planar Laser Induced Fluorescence (PLIF) visualizations have been made in a turbulent boundary layer over a rough wall. The roughness consists of square bars placed transversely to the flow at a pitch to height ratio of 11. The near wall region flow is dominated by coherent structures associated with the shear layers which originate at the downstream edge of a roughness element and reattach on the wall upstream of the subsequent element. Shear layer vortices shed downstream a roughness elements impact on the consecutive element producing intermittent form drag and strong turbulence production.