Hostname: page-component-745bb68f8f-g4j75 Total loading time: 0 Render date: 2025-01-09T22:10:29.855Z Has data issue: false hasContentIssue false
  • English
  • Français

Scalar diffusion in simulated helical turbulence with molecular diffusivity

Published online by Cambridge University Press:  20 April 2006

I. T. Drummond ,
S. Duane  and
R. R. Horgan
I. T. Drummond
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW
S. Duane
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW
R. R. Horgan
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW
Get access Rights & Permissions [Opens in a new window]

Abstract

We extend the simulation techniques of Kraichnan (1970, 1976) to study the effective diffusivity of a scalar field in a turbulent fluid. In our model we have introduced an adjustable helicity parameter and a technique for simulating molecular diffusivity. The results show that for non-helical turbulence the self-consistent perturbation theory of Phythian & Curtis (1978) gives excellent values for the effective diffusivity over a wide range of values for both the molecular diffusivity and the parameters describing the turbulence.

This ceases to be the case immediately the helicity is given a non-zero value. Wide departures are observed between the theoretical calculation and the simulation. Our conclusion is that non-perturbative effects are very important in the presence of helicity.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 138 , January 1984 , pp. 75 - 91
Copyright
© 1984 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Drummond, I. T. 1982 Path-integral methods for turbulent diffusion J. Fluid Mech. 123, 59.Google Scholar
Drummond, I. T., Duane, S. & Horgan, R. R. 1983 The stochastic method for numerical simulations: higher order corrections. Nucl. Phys. B220 [FS8], 119.Google Scholar
Kraichnan, R. H. 1970 Diffusion by a random velocity field. Phys. Fluids 13. 22.Google Scholar
Kraichnan, R. H. 1976 Diffusion of passive scalar and magnetic fields by helical turbulence J. Fluid Mech. 77, 753.Google Scholar
Kraichnan, R. H. 1977 Lagrangian velocity covariance in helical turbulence J. Fluid Mech. 81, 385.Google Scholar
Phythian, R. & Curtis, W. D. 1978 The effective long-time diffusivity for a passive scalar field in a Gaussian model flow J. Fluid Mech. 89, 241.Google Scholar
Saffman, P. G. 1960 On the effect of molecular diffusivity in turbulent diffusion J. Fluid Mech. 8, 273.Google Scholar
Moffatt, H. K. 1979 Magnetic Field Generation in Electrically Conducting Fluids. Cambridge University Press.
Steenbeck, M., Krause, F. & Radler, K.-H. 1966 Z. Naturforsch. 21a, 369.