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Probability distribution function for self-organization of shear flows

Kim, E.J., Liu, H.L. and Anderson, J. (2009) Probability distribution function for self-organization of shear flows. Physics of Plasmas, 16 (5). Art. No.052304. ISSN 1070-664X

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Abstract

The first prediction of the probability distribution function (PDF) of self-organized shear flows is presented in a nonlinear diffusion model where shear flows are generated by a stochastic forcing while diffused by a nonlinear eddy diffusivity. A novel nonperturbative method based on a coherent structure is utilized for the prediction of the strongly intermittent exponential PDF tails of the gradient of shear flows. Numerical simulations using Gaussian forcing not only confirm these predictions but also reveal the significant contribution from the PDF tails with a large population of supercritical gradients. The validity of the nonlinear diffusion model is then examined using a threshold model where eddy diffusivity is given by discontinuous values, elucidating an important role of relative time scales of relaxation and disturbance in the determination of the PDFs.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 American Institute of Physics. This is an author produced version of a paper subsequently published in Physics of Plasmas. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Fokker-Planck equation; numerical analysis; plasma flow; plasma nonlinear processes; plasma simulation; plasma transport processes; shear flow; stochastic processes
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 29 Jun 2009 15:30
Last Modified: 08 Feb 2013 16:58
Published Version: http://dx.doi.org/10.1063/1.3132631
Status: Published
Publisher: American Institute of Physics
Refereed: Yes
Identification Number: 10.1063/1.3132631
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/8736

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