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A closure model for turbulent convection. Application to the excitation of p modes

Published online by Cambridge University Press:  01 August 2006

K. Belkacem ,
R. Samadi ,
M.-J. Goupil ,
F. Kupka  and
F. Baudin
K. Belkacem
Affiliation:
Observatoire de Paris, LESIA, CNRS UMR 8109, 92195 Meudon, France email: kevin.belkacem@obspm.fr
R. Samadi
Affiliation:
Observatoire de Paris, LESIA, CNRS UMR 8109, 92195 Meudon, France email: kevin.belkacem@obspm.fr
M.-J. Goupil
Affiliation:
Observatoire de Paris, LESIA, CNRS UMR 8109, 92195 Meudon, France email: kevin.belkacem@obspm.fr
F. Kupka
Affiliation:
Max-Planck-Institute for Astrophysics, Karl-Schwarzschild Str. 1, 85741 Garching, Germany
F. Baudin
Affiliation:
Institut d'Astrophysique Spatiale, CNRS/Université Paris XI UMR 8617, 91405 Orsay Cedex, France
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Abstract

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Oscillations of stellar p modes excited by turbulent convection are investigated. In the uppermost part of the solar convection zone, radiative cooling is responsible for the formation of turbulent plumes, hence the medium is characterized with downdrafts and updrafts. The motivation is to take the asymmetry of up- and downflows created by turbulent plumes into account through an adapted closure model. We built a generalized two-scale mass-flux model (GTFM) that considers both the skew introduced by the presence of two flows and the effect of turbulence onto each flow. In order to apply the GTFM to the solar case, we introduce the plume dynamics as modelled by Rieutord & Zahn (1995) and construct a closure model with plumes (CMP). The CMP enables to express third- and fourth-order velocity correlation products in terms of the second-order ones. When comparing with 3D numerical simulation results, the CMP improves the agreement for the fourth order moments in comparison with the quasi-normal approximation (QNA) or the classical mass-flux model (MFM). This excitation model reproduces the maximum of the power supplied to solar p modes, when compared with GOLF observations.

Keywords

ConvectionturbulenceSun: oscillations
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S239: Convection in Astrophysics , August 2006 , pp. 376 - 378
Copyright
Copyright © International Astronomical Union 2007

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