Diffusion of passive scalar in a finite-scale random flow

Alexander A. Schekochihin; Peter H. Haynes; Steven C. Cowley

doi:10.1103/PhysRevE.70.046304

Diffusion of passive scalar in a finite-scale random flow

Alexander A. Schekochihin, Peter H. Haynes, Steven C. Cowley

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

A model of the decay of scalar variance in a single-scale random velocity field was considered. It was emphasized that in any laboratory experiment aiming to test the results, the stirring must be done at scales substantially smaller than the system size. The key factor was found to be the statistics of fluid displacements, which were integrals of velocity and were finite-time correlated even for a white-in-time velocity. A set up allows to show experimentally that the global mixing rate was much smaller than that predicted by the Lagrangian-stretching theories and consistent with the box-scale turbulent-diffusion rate.

Original language	English (US)
Article number	046304
Pages (from-to)	046304-1-046304-7
Journal	Physical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume	70
Issue number	4 2
DOIs	https://doi.org/10.1103/PhysRevE.70.046304
State	Published - Oct 2004
Externally published	Yes

All Science Journal Classification (ASJC) codes

Condensed Matter Physics
Statistical and Nonlinear Physics
Statistics and Probability

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10.1103/PhysRevE.70.046304

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title = "Diffusion of passive scalar in a finite-scale random flow",

abstract = "A model of the decay of scalar variance in a single-scale random velocity field was considered. It was emphasized that in any laboratory experiment aiming to test the results, the stirring must be done at scales substantially smaller than the system size. The key factor was found to be the statistics of fluid displacements, which were integrals of velocity and were finite-time correlated even for a white-in-time velocity. A set up allows to show experimentally that the global mixing rate was much smaller than that predicted by the Lagrangian-stretching theories and consistent with the box-scale turbulent-diffusion rate.",

author = "Schekochihin, {Alexander A.} and Haynes, {Peter H.} and Cowley, {Steven C.}",

note = "Funding Information: We thank J.-L. Thiffeault, A. Kerstein, and M. Gonzalez for stimulating discussions. A.A.S. was supported by the Leverhulme Trust through the UKAFF.",

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AU - Haynes, Peter H.

AU - Cowley, Steven C.

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Diffusion of passive scalar in a finite-scale random flow

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