TURBULENCE IN ASTROPHYSICS: Stars 1
Turbulence is ubiquitous in astrophysics, ranging from cosmology, interstellar medium to stars, supernovae, accretion disks, etc. Large scales and small viscosities combine to form large Reynolds numbers. Because it is not possible in a single article to review all the above scenarios, we limit ours...
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| Vydané v: | Annual review of fluid mechanics Ročník 30; číslo 1; s. 167 - 198 |
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| Hlavní autori: | , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
Palo Alto, CA 94303-0139
Annual Reviews
01.01.1998
4139 El Camino Way, P.O. Box 10139 USA |
| Predmet: | |
| ISSN: | 0066-4189, 0066-4189 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | Turbulence is ubiquitous in astrophysics, ranging from cosmology,
interstellar medium to stars, supernovae, accretion disks, etc. Large scales
and small viscosities combine to form large Reynolds numbers. Because it is not
possible in a single article to review all the above scenarios, we limit
ourselves to stars, in which thermal instabilities give rise to turbulent
convection as the dominant heat transport mechanism. (Accretion disks, where
shear instabilities dominate the outward transport of angular momentum, will be
the subject of a second article, planned for Volume 31.) Because of the lack of
a satisfactory theory, turbulence constitutes a bottleneck that prevents
astrophysical models from being fully predictive. Because continued use of
phenomenological turbulence expressions would make astrophysical models
perennially unpredictive, a way must be found to make astrophysical models as
prognostic as possible. In addition to the difficulties brought about by
turbulence, astrophysical settings introduce "malicious
conditions," of which the most refractory to a satisfactory
quantification are compressibility (caused by the large density excursions that
characterize convective zones in stars) and rotation. Basic understanding of
how they affect turbulence in general is still rather sketchy. Reasons for the
choice of stars and accretion disks as prototype examples are the following:
The underlying instabilities are very basic; laboratory and direct numerical
simulations data help constrain theoretical models; and new observational data,
especially from helioseismology, help discriminate among different models with
unprecedented accuracy. |
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| ISSN: | 0066-4189 0066-4189 |
| DOI: | 10.1146/annurev.fluid.30.1.167 |