Exact coherent states in channel flow

D. P. Wall, M. Nagata

研究成果: Contribution to journalArticle査読

6 被引用数 (Scopus)

抄録

Three spatially extended travelling wave exact coherent states, together with one spanwise-localised state, are presented for channel flow. Two of the extended flows are derived by homotopy from solutions to the problem of channel flow subject to a spanwise rotation investigated by Wall & Nagata (J. Fluid Mech., vol. 727, 2013, pp. 523-581). Both these flows are asymmetric with respect to the channel centreplane, and feature streaky structures in streamwise velocity flanked by staggered vortical structures. One of these flows features two streak/vortex systems per spanwise wavelength, while the other features one such system. The former substantially reduces the value of the lowest Reynolds number at which channel flow solutions ,other than the basic flow, are known to exist down to 665. The third flow has, in contrast, half-turn rotational symmetry about a streamwise axis through a point on the channel centreplane, and is found to be the flow from which one of the asymmetric flows bifurcates in a symmetry-breaking bifurcation. This flow is found to exist on an isolated bifurcation branch, whose upper and lower branches both lie on the boundary basin separating initial conditions that lead to turbulent events, and those that directly decay back to laminar flow. The structure of this flow, in which the disturbance to the basic flow is concentrated in a core region in a spanwise period, allowed the derivation of a corresponding spanwise-localised flow, which is also discussed.

本文言語英語
ページ(範囲)444-468
ページ数25
ジャーナルJournal of Fluid Mechanics
788
DOI
出版ステータス出版済み - 1 8 2016
外部発表はい

All Science Journal Classification (ASJC) codes

  • 凝縮系物理学
  • 材料力学
  • 機械工学

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