ENS Radioastronomy Laboratory - LERMA UMR 8112

Journal Club//Séminaire Daniel Lecoanet

Last update 09-19-2014 10:52 am / Jean-François Rabasse

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(This text is not available in English, we apologize.)

ABSTRACT:

 

Thermal conduction is an important energy transfer and damping mechanism in astrophysical flows. Fourier's law (the heat flux is proportional to the negative temperature gradient, leading to temperature diffusion) is a well-known empirical model of thermal conduction. However, entropy diffusion has emerged as an alternative thermal conduction model, despite not ensuring the monotonicity of entropy.

This paper investigates the differences between temperature and entropy diffusion for both linear internal gravity waves and weakly nonlinear convection. In addition to simulating the two thermal conduction models with the fully compressible Navier-Stokes equations, we also study their effects in the reduced, "sound-proof" anelastic and pseudo-incompressible equations.

We found that in the linear and weakly nonlinear regime, temperature and entropy diffusion give quantitatively similar results, although there are some larger errors in the pseudo-incompressible equations with temperature diffusion due to inaccuracies in the equation of state.

Extrapolating our weakly nonlinear results, we speculate that differences between temperature and entropy diffusion might become more important for strongly turbulent convection

 

QUELQUES REFERENCES (récentes):

1) Lecoanet et al., Conduction in low mach number flows: part I linear & weakly nonlinear regimes.

(En pièce jointe)

 

2) Calkins et al, Rapidly rotating compressible convection and the shortcomings of the anelastic equations.

http://arxiv.org/abs/1409.1959