The roles of shear and cross-correlations on the fluctuation levels in simple stochastic models. Revision

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Highly simplified models of random flows interacting with background microturbulence are analyzed. In the limit of very rapid velocity fluctuations, it is shown rigorously that the fluctuation level of a passively advected scalar is not controlled by the rms shear. In a model with random velocities dependent only on time, the level of cross-correlations between the flows and the background turbulence regulates the saturation level. This effect is illustrated by considering a simple stochastic-oscillator model, both exactly and with analysis and numerical solutions of the direct-interaction approximation. Implications for the understanding of self-consistent turbulence are discussed briefly.

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374 Kilobytes pages

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Krommes, J.A. November 3, 1999.

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Description

Highly simplified models of random flows interacting with background microturbulence are analyzed. In the limit of very rapid velocity fluctuations, it is shown rigorously that the fluctuation level of a passively advected scalar is not controlled by the rms shear. In a model with random velocities dependent only on time, the level of cross-correlations between the flows and the background turbulence regulates the saturation level. This effect is illustrated by considering a simple stochastic-oscillator model, both exactly and with analysis and numerical solutions of the direct-interaction approximation. Implications for the understanding of self-consistent turbulence are discussed briefly.

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374 Kilobytes pages

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INIS; OSTI as DE00751203

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  • Other Information: PBD: 3 Nov 1999

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  • Report No.: PPPL--3377Revised
  • Grant Number: AC02-76CH03073
  • DOI: 10.2172/751203 | External Link
  • Office of Scientific & Technical Information Report Number: 751203
  • Archival Resource Key: ark:/67531/metadc709846

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  • November 3, 1999

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  • Sept. 12, 2015, 6:31 a.m.

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  • April 15, 2016, 7:37 p.m.

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Krommes, J.A. The roles of shear and cross-correlations on the fluctuation levels in simple stochastic models. Revision, report, November 3, 1999; Princeton, New Jersey. (digital.library.unt.edu/ark:/67531/metadc709846/: accessed December 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.