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

Journal Article · Mon May 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/769/1/1· OSTI ID:22126672

Viallet, Maxime ^[1]; Meakin, Casey; Mocak, Miroslav ^[2]; Arnett, David ^[3]

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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)

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.

• OSTI ID: 22126672
• Journal Information: Astrophysical Journal, Vol. 769, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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