[Table of Contents]

Plasma and Fusion Research

Volume 9, 3401019 (2014)

Regular Articles

Spectrum of Passive Scalar at Very High Schmidt Number in Turbulence
Toshiyuki GOTOH, Takeshi WATANABE and Hideaki MIURA1)
Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 21 November 2013 / Accepted 3 February 2014 / Published 14 March 2014)

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.

Keywords

passive scalar spectrum, universality, turbulence, hybrid method, combined compact finite difference

DOI: 10.1585/pfr.9.3401019

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This paper may be cited as follows:

Toshiyuki GOTOH, Takeshi WATANABE and Hideaki MIURA, Plasma Fusion Res. 9, 3401019 (2014).