RESUMO

The characteristics of three-dimensional intense uv coherent structures (Qs) in a strongly decelerated large-velocity-defect boundary layer are analysed by direct numerical simulation. The Reynolds number close to the exit is Re_θ = 2175 and the shape factor H = 2.5. In the region of large-velocity-defect flow, the maxima of Reynolds stresses and of production of turbulent kinetic energy are located in the middle of the boundary layer. The Q2 and Q4 structures are found to be different from those of turbulent channel flows studied by Lozano-Duran et al. (J. Fluid Mech., vol. 694, 2012). They are less streamwise elongated and less present near the wall. Moreover, contrary to channel flows, wall-detached Q2 and Q4 structures are more frequent and carry a much larger amount of the Reynolds shear stress.