Turbulence regulation by stochastic zonal flows in dynamical models

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Abstract

A theory of turbulence reduction by zonal flows is presented in the interchange turbulence model. Zonal flows with a finite correlation time τZF are shown to lead to a significant reduction in particle transport and turbulence amplitude, with the scalings «n vx » ∝ τD Ωeff -1 ∝ Ωeff -32, « n2 » ∝ τD ∝ Ωeff -12, and « vx2 » ∝ τD Ωeff -2 ∝ Ωeff -52. Here, Ωeff = τZF Ωrms2, τD = (τη Ωeff) 12, and τη are the effective shearing rate, effective decorrelation time, and diffusive turbulent scattering time, respectively. Compared to the transport of passive scalar fields [E. Kim and P. H. Diamond, Phys. Plasmas, 11, L77 (2004)], the reduction is much more severe due to the suppression of turbulent velocity. However, the overall transport and turbulence amplitude are still larger compared with the case of coherent shearing because shearing by random zonal flows with a finite correlation time is less efficient, with a longer decorrelation time τD than (τη Ω2) 13 in the case of coherent shearing.

Original languageEnglish
Article number090902
Number of pages4
JournalPhysics of Plasmas
Volume12
Issue number9
DOIs
Publication statusPublished - 21 Sep 2005
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics

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