SPATIAL FEATURES OF REYNOLDS-STRESS CARRYING STRUCTURES IN TURBULENT BOUNDARY LAYERS WITH PRESSURE GRADIENT

Two direct numerical simulation databases are examined to understand the effect of mean shear on the outer layer turbulence of pressure-gradient turbulent boundary layers along with two homogeneous shear turbulence databases. We compare the shape of Reynolds-shear-stress carrying structures in all cases, choosing five streamwise locations in the turbulent boundary layers with different pressure gradient sign and/or intensity, as well as upstream history. The results indicate that the shape of the structures is very similar across all flows when their size is between 1 to 10 Corrsin length scales. This suggests that mean shear acts in a similar manner in all these flows to generate Reynolds-shear-stress carrying structures and therefore turbulence production.