Effects of transition on the Reynolds-stress producing events in a turbulent boundary layer

The effects of transition conditions on the development of coherent structures associated with the Reynolds stress production process in turbulent boundary layers is investigated. Two types of transition conditions are investigated: a sandpaper trip and a 'fence-type' trip. Both conditions are seen to produce an equilibrium turbulent boundary over the Reynolds numbers investigated. Measurements of the streamwise velocity are made over a Reynolds number range greater than 1800 and less than 6000 to study various statistics resulting from the u-level and VITA detection schemes. A two-dimensional sampling grid is used to investigate the effect of the two transition conditions upon an 'integral-scale' measure of the ensemble-averaged structure associated with a wall-shear-stress detection scheme. The results suggest that the frequency of occurrence of u-level and VITA events are insensitive to transition conditions, whereas a small change is seen regarding the 'integral-scale' of the ensemble-averaged structure associated with the wall-shear-stress detection scheme.