Large-scale intermittency and rare events boosted at dimensional crossover in anisotropic turbulence

Keiko Takahashi, Koji Goto, Ryo Onishi, Masatoshi Imada

研究成果: Article査読

抄録

Understanding rare events in turbulence provides a basis for the science of extreme weather, for which the atmosphere is modeled by Navier-Stokes equations (NSEs). In solutions of NSEs for isotropic fluids, various quantities, such as fluid velocities, roughly follow Gaussian distributions, where extreme events are prominent only in small-scale quantities associated with the dissipation-dominating length scale or anomalous scaling regime. Using numerical simulations, this study reveals another universal promotion mechanism at much larger scales if three-dimensional fluids accompany strong two-dimensional anisotropies, as is the case in the atmosphere. The dimensional crossover between two and three dimensions generates prominent fat-tailed non-Gaussian distributions with intermittency accompanied by colossal chainlike structures with densely populated self-organized vortices (serpentinely organized vortices). The promotion is caused by a sudden increase of the available phase space at the crossover length scale. Since the discovered intermittency can involve much larger energies than those in the conventional intermittency in small spatial scales, it governs extreme events and chaotic unpredictability in the synoptic weather system.

本文言語English
論文番号124607
ジャーナルPhysical Review Fluids
3
12
DOI
出版ステータスPublished - 2018 12
外部発表はい

ASJC Scopus subject areas

  • 計算力学
  • モデリングとシミュレーション
  • 流体および伝熱

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