Passive scalar diffusion as a damped wave
Abstract
Three-dimensional turbulence simulations are used to show that the turbulent root mean square velocity is an upper bound of the speed of turbulent diffusion. There is a close analogy to magnetic diffusion where the maximum diffusion speed is the speed of light. Mathematically, this is caused by the inclusion of the Faraday displacement current which ensures that causality is obeyed. In turbulent diffusion, a term similar to the displacement current emerges quite naturally when the minimal tau approximation is used. Simulations confirm the presence of such a term and give a quantitative measure of its relative importance.
Cite
@article{arxiv.physics/0404118,
title = {Passive scalar diffusion as a damped wave},
author = {Axel Brandenburg and Petri Käpylä and Amjed Mohammed},
journal= {arXiv preprint arXiv:physics/0404118},
year = {2007}
}
Comments
4 pages, 3 figures, to appear in Progress in Turbulence, Eds. M. Oberlack, J. Peinke, A. Kittel, S. Barth. Springer-Verlag, 2004