Self-sustained process at large scales in turbulent channel flow

Phys Rev Lett. 2010 Jul 23;105(4):044505. doi: 10.1103/PhysRevLett.105.044505. Epub 2010 Jul 23.


Large-scale motions, important in turbulent shear flows, are frequently attributed to the interaction of structures at smaller scales. Here we show that, in a turbulent channel at Re{τ}≈550, large-scale motions can self-sustain even when smaller-scale structures populating the near-wall and logarithmic regions are artificially quenched. This large-scale self-sustained mechanism is not active in periodic boxes of width smaller than L{z}≈1.5h or length shorter than L{x}≈3h which correspond well to the most energetic large scales observed in the turbulent channel.