European Turbulence Conference 2015

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16:45
15 mins

Detached coherent structures in channel revisited: comparison with homogeneous shear turbulence
Siwei Dong, Adrián Lozano Durán, Atsushi Sekimoto, Javier Jiménez

Session: Wall-bounded flows 2
Session starts: Tuesday 25 August, 15:00
Presentation starts: 16:45
Room: Room I

Siwei Dong (Universidad Politécnica de Madrid)
Adrián Lozano Durán (Universidad Politécnica de Madrid)
Atsushi Sekimoto (Universidad Politécnica de Madrid)
Javier Jiménez (Universidad Politécnica de Madrid)

Abstract:
Coherent structures in statistically-stationary homogeneous shear turbulence (HST) are compared with those of the detached family in channels. Similarly to attached ones, detached Qs in channels form streamwise trains of side-by-side groups of a Q2 and a Q4. This is also true in HST. Contrary to attached structures, but similarly to those in HST, detached Q4s in channels are comparable in size to their related high-streamwise velocity streaks. Vortex clusters tend to associate with Q2s and Q4s, equally distributed between them in HST but more closely with Q2s in channels. The results strongly suggest that coherent structures in channels are not particularly associated with the wall, or even with a given shear profile.