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The Mixing Length Ratio, Eddy Diffusivity and Acoustic Waves

Published online by Cambridge University Press:  12 April 2016

Kwing L. Chan
Affiliation:
Applied Research Corp. Landover, Maryland, U.S.A.
Sabatino Sofia
Affiliation:
Center fo Solar and Space Research, Yale University New Haven, Connecticut, U.S.A.

Extract

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Many processes in the convection zone of a star affect the evolution and the atmospheric diagnostics. Here, a progress report is given on our numerical study of some convection related phenomena. The numerical results are obtained by solving the Navier Stokes equations in a three dimensional rectangular domain. The units are chosen such that the initial temperature, pressure, density, and the depth of the domain are all normalized to 1.

The mixing length theory relates the convective (enthalpy) flux FC to the envelope structure quite well (Chan and Sofia 1987). For efficient convection that occurs in deep convective regions, the numerical results are compatible with a mixing length ratio of 2.1. The mixing length theory fails to address the significance of the flux of kinetic energy FKE (see Figure 1). FKE is negative and has a magnitude comparable to the total flux. These results are qualitatively similar to those of two dimensional computations (Hurlburt et. al. 1984).

Type
Part II. Mass-Losing Stars in Different Stages of Evolution
Copyright
Copyright © Springer-Verlag 1988

References

Chan, K.L. and Sofia, S. 1987, SCIENCE, 235, 465.Google Scholar
Hurlburt, N.E., Toomre, J., and Massaguer, J.M. 1984, Ap. J., 282, 557.Google Scholar