## Publication Abstracts

### Canuto 1989

**217**, 333-343.

The standard MLT assumed a) that the largest eddies are the only ones that contribute to convection and b) that they are isotropic. These two requirements are internally inconsistent since it is experimentally known that only small eddies are isotropic, while large eddies exhibit large degrees of anisotropy. In this paper we present a new model: anisotropic mixing length theory, AMLT, together with a model that relates the anisotropy to other quantities of the problem. The new AMLT equations are solved for two cases of interest in stellar structure calculations.

In the first case, the gradients ∇_{r} and ∇_{ad} are considered known, and the resulting expression for ∇ and ∇ derived. The basic AMLT relations are given in two equivalent representations: Eqs. (49)-(52) and/or Eqs. (53)-(54). It is shown that: 1) The value of ∇ - ∇_{ad} from the AMLT is up to two orders of magnitude larger than the corresponding MLT value, Eq. (60). 2) In the physically important case of large degrees of anisotropy, the turbulent velocity in the AMLT is lower than the corresponding MLT value by a factor of 2, Eq. (67). This may help lessen the problem of overshooting.

In the second case, the gradients ∇ and ∇_{ad}, are considered known and the resulting expressions for ∇_{r} and ∇' are derived, together with the expressions for the convective flux and the turbulent velocity, Eqs. (71), (73), (74) and (75). For the case of large anisotropies, the AMLT can be solved analytically, Eqs. (79)-(83). The convective flux, the convective velocities, the temperature excess, and the radiative gradient, are smaller than the MLT relations by the factors x^{-1}, x^{-1/2}, x^{-1/2}, and x^{-1}, respectively, where x ≫ 1 is given in terms of known variables via Eq. (79).

The present formalism is valid only in the optically thick case.

- Get PDF (1.4 MB. Document is scanned, no OCR.)
- PDF documents require the free Adobe Reader or compatible viewing software to be viewed.

**Export citation:**
[ BibTeX ] [ RIS ]

#### BibTeX Citation

@article{ca04810k, author={Canuto, V. M.}, title={AMLT: Anisotropic mixing length theory}, year={1989}, journal={Astronomy and Astrophysics}, volume={217}, pages={333--343}, }

[ Close ]

#### RIS Citation

TY - JOUR ID - ca04810k AU - Canuto, V. M. PY - 1989 TI - AMLT: Anisotropic mixing length theory JA - Astron. Astrophys. JO - Astronomy and Astrophysics VL - 217 SP - 333 EP - 343 ER -

[ Close ]