title: Self-sustained process at large scales in turbulent channel flow.
abstract: 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.
authors.affiliation: LadHyX, CNRS-Ecole Polytechnique, 91128 Palaiseau, France. yongyun@ladhyx.polytechnique.fr
authors.forename: Yongyun
authors.initials: Y
authors.lastname: Hwang
authors.forename: Carlo
authors.initials: C
authors.lastname: Cossu