Conditional analysis of the wake of a cylinder immersed in a turbulent boundary layer

The aim of this study was to explore interactions between large-scale coherent structures in a turbulent boundary layer and small-scale vortices shedding from a cylinder wake. Experimental 2D particle image velocimetry data for a cylinder immersed at six different wall-normal distances in a turbulent boundary layer (D/δ = 0.05, where D is the cylinder diameter and δ is the boundary layer at 99% of the freestream velocity) over a flat plate were studied. In this presentation, conditional averages of the streamwise, wall-normal, and shear Reynolds stresses based on the large-scale velocity at streamwise positions between x=δ and x=3δ are presented. At the different streamwise locations, the stresses show evidence of amplitude modulation-like behavior in the wake region. Additionally, it will be shown that the wall-normal location of the peak of the streamwise stresses associated with the cylinder's wake is dependent on the sign of the local large-scale structure.