Publication Abstracts

Canuto and Battaglia 1988

Canuto, V.M., and A. Battaglia, 1988: Turbulent diffusivity. Astron. Astrophys., 193, 313-326.

A reliable quantification of many problems of astrophysical interest, e.g. mixing in the interior of the sun with implication for the solar neutrino problem, chemical evolution of the galaxy with cosmological consequences, grain sedimentation in the primitive solar nebula, etc., requires the knowledge of the turbulent diffusivity tensor Dij. In this paper, we treat two problems.

First, given a passive scalar (e.g., a particle) embedded in an otherwise turbulent medium, and responding to it via frictional forces, we derive an expression for its turbulent velocity, Eq. (52), as well as for the components of Dij for an axisymmetric case. These formulae are relevant to the problem of grain sedimentation in the primitive solar nebula.

Second, when the velocity of the contaminant coincides with that of the fluid, we show that the diffusivity tensor becomes diagonal, i. e., Dij = DTδij and we provide an expression for DT. This quantity is of interest, for example, to the astrophysical case of mixing in the interior of the sun.

In addition to the general formula, which involves the contribution of the whole spectrum of the turbulent eddies, we also derive a simplified formula for Dt, which yields a remarkably good approximation to the exact formula.

To test our results, we have compared our predicted values for DT with recent results from full numerical simulation studies as well as with laboratory data on shear turbulence. The agreement is good.

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BibTeX Citation

  author={Canuto, V. M. and Battaglia, A.},
  title={Turbulent diffusivity},
  journal={Astronomy and Astrophysics},

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RIS Citation

ID  - ca03220j
AU  - Canuto, V. M.
AU  - Battaglia, A.
PY  - 1988
TI  - Turbulent diffusivity
JA  - Astron. Astrophys.
JO  - Astronomy and Astrophysics
VL  - 193
SP  - 313
EP  - 326
ER  -

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