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Title: TURBULENT CONVECTION IN STELLAR INTERIORS. III. MEAN-FIELD ANALYSIS AND STRATIFICATION EFFECTS

Abstract

We present three-dimensional implicit large eddy simulations of the turbulent convection in the envelope of a 5 M{sub Sun} red giant star and in the oxygen-burning shell of a 23 M{sub Sun} supernova progenitor. The numerical models are analyzed in the framework of one-dimensional Reynolds-Averaged Navier-Stokes equations. The effects of pressure fluctuations are more important in the red giant model, owing to larger stratification of the convective zone. We show how this impacts different terms in the mean-field equations. We clarify the driving sources of kinetic energy, and show that the rate of turbulent dissipation is comparable to the convective luminosity. Although our flows have low Mach numbers and are nearly adiabatic, our analysis is general and can be applied to photospheric convection as well. The robustness of our analysis of turbulent convection is supported by the insensitivity of the mean-field balances to linear mesh resolution. We find robust results for the turbulent convection zone and the stable layers in the oxygen-burning shell model, and robust results everywhere in the red giant model, but the mean fields are not well converged in the narrow boundary regions (which contain steep gradients) in the oxygen-burning shell model. This last result illustrates themore » importance of unresolved physics at the convective boundary, which governs the mixing there.« less

Authors:
 [1]; ;  [2];  [3]
  1. Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom)
  2. Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
  3. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
Publication Date:
OSTI Identifier:
22126672
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 769; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONVECTION; FLUCTUATIONS; HYDRODYNAMICS; LARGE-EDDY SIMULATION; LAYERS; LUMINOSITY; MEAN-FIELD THEORY; MIXING; NAVIER-STOKES EQUATIONS; OXYGEN; RED GIANT STARS; RESOLUTION; REYNOLDS NUMBER; SHELL MODELS; STAR EVOLUTION; STRATIFICATION; SUPERNOVAE; THREE-DIMENSIONAL CALCULATIONS; TURBULENCE

Citation Formats

Viallet, Maxime, Meakin, Casey, Mocak, Miroslav, and Arnett, David. TURBULENT CONVECTION IN STELLAR INTERIORS. III. MEAN-FIELD ANALYSIS AND STRATIFICATION EFFECTS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/769/1/1.
Viallet, Maxime, Meakin, Casey, Mocak, Miroslav, & Arnett, David. TURBULENT CONVECTION IN STELLAR INTERIORS. III. MEAN-FIELD ANALYSIS AND STRATIFICATION EFFECTS. United States. https://doi.org/10.1088/0004-637X/769/1/1
Viallet, Maxime, Meakin, Casey, Mocak, Miroslav, and Arnett, David. Mon . "TURBULENT CONVECTION IN STELLAR INTERIORS. III. MEAN-FIELD ANALYSIS AND STRATIFICATION EFFECTS". United States. https://doi.org/10.1088/0004-637X/769/1/1.
@article{osti_22126672,
title = {TURBULENT CONVECTION IN STELLAR INTERIORS. III. MEAN-FIELD ANALYSIS AND STRATIFICATION EFFECTS},
author = {Viallet, Maxime and Meakin, Casey and Mocak, Miroslav and Arnett, David},
abstractNote = {We present three-dimensional implicit large eddy simulations of the turbulent convection in the envelope of a 5 M{sub Sun} red giant star and in the oxygen-burning shell of a 23 M{sub Sun} supernova progenitor. The numerical models are analyzed in the framework of one-dimensional Reynolds-Averaged Navier-Stokes equations. The effects of pressure fluctuations are more important in the red giant model, owing to larger stratification of the convective zone. We show how this impacts different terms in the mean-field equations. We clarify the driving sources of kinetic energy, and show that the rate of turbulent dissipation is comparable to the convective luminosity. Although our flows have low Mach numbers and are nearly adiabatic, our analysis is general and can be applied to photospheric convection as well. The robustness of our analysis of turbulent convection is supported by the insensitivity of the mean-field balances to linear mesh resolution. We find robust results for the turbulent convection zone and the stable layers in the oxygen-burning shell model, and robust results everywhere in the red giant model, but the mean fields are not well converged in the narrow boundary regions (which contain steep gradients) in the oxygen-burning shell model. This last result illustrates the importance of unresolved physics at the convective boundary, which governs the mixing there.},
doi = {10.1088/0004-637X/769/1/1},
url = {https://www.osti.gov/biblio/22126672}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 769,
place = {United States},
year = {2013},
month = {5}
}