Plasma and Fusion Research
Online ISSN : 1880-6821
ISSN-L : 1880-6821
Regular Articles
Spectrum of Passive Scalar at Very High Schmidt Number in Turbulence
Toshiyuki GOTOHTakeshi WATANABEHideaki MIURA
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2015 Volume 9 Pages 3401019

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Abstract

A hybrid code which uses the spectral method for an incompressible fluid and the combined compact finite difference method for passive scalar is developed and applied to compute the spectrum of the passive scalar variance in turbulence at very high Schmidt numbers up to 1000. The accuracy and efficiency of the hybrid code are found to be very satisfactory when compared to the full spectral computation. The scalar spectrum in the viscous-convective range by direct numerical simulation is found to obey k−1 power law and to exponentially decay in the far diffusive range, and compared to Kraichnan’s spectrum. It is argued that the exponential decay of the spectrum in the far diffusive range is due to the intermittency effect of the velocity field.

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© 2015 by The Japan Society of Plasma Science and Nuclear Fusion Research
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