NEAR-wall influence of large-scale motions in high reynolds number turbulent boundary layers

Abstract

A spanwise array of surface hot-film shear-stress sensors and a traversing hot-wire located directly above one of these sensors are used to examine the relationship between skin-friction fluctuations and the velocity fluctuations in the boundary layer. Experiments are performed in a high Reynolds number turbulent boundary layer at Reθ ≈ 39000. The shear-stress data indicate the presence of large-scale structures that extend to large streamwise distances. These structures appear to be the footprint of the large-scale superstructures that are present in the logarithmic region. Conditional averages computed based on low and high skin-friction events indicate the presence of a forward-leaning lo..