Intense Reynolds-stress events in turbulent ducts

The aim of the present work is to investigate role intense Reynolds shear-stress events in generation secondary flow turbulent ducts. We consider connected regions where product instantaneous fluctuations two velocity components higher than a threshold based on long-time turbulence statistics, spirit three-dimensional quadrant analysis proposed by Lozano-Durán et al. (J. Fluid Mech., vol. 694, 2012, pp. 100–130). examine both geometrical properties these structures and their contribution mean in-plane components, we perfom comparison with channel at similar number. certain quantity defined as ensemble average over detected coherent structures, weighted own occupied volume fraction. In core region duct, wall-normal component very good agreement that channel, despite presence former. Additionally, shapes objects do not differ significantly flows. corner proximity walls affects vertical velocity. However, such less relevant complementary portion included objects. Our results show strong are affected but, important dynamics wall-bounded flows, relatively low, corner.