Efficient turbulent compressible convection in the deep stellar atmosphere

【摘要】 We report on an application of gas-kinetic BGK scheme to the computation of turbulent compressible convection in the stellar interior.After incorporating the Sub-grid Scale(SGS) turbulence model into the BGK scheme,we tested the effects of numerical parameters on the quantitative relationships among the thermodynamic variables,their fluctuations and correlations in a very deep,initially gravity-stratified stellar atmosphere.Comparison indicates that the thermal properties and dynamic properties are dominated by different aspects of numerical models separately.An adjustable Deardorff constant in the SGS model cμ = 0.25 and an amplitude of artificial viscosity in the gas-kinetic BGK scheme C2 = 0 are appropriate for the current study.We also calculated the density-weighted auto-and cross-correlation functions in Xiong’s turbulent stellar convection theory based on which the gradient type of models of the non-local transport and the anisotropy of the turbulence were preliminarily studied.No universal relations or con-stant parameters were found for these models.更多还原

【Abstract】 We report on an application of gas-kinetic BGK scheme to the computation of turbulent compressible convection in the stellar interior.After incorporating the Sub-grid Scale(SGS) turbulence model into the BGK scheme,we tested the effects of numerical parameters on the quantitative relationships among the thermodynamic variables,their fluctuations and correlations in a very deep,initially gravity-stratified stellar atmosphere.Comparison indicates that the thermal properties and dynamic properties are dominated by different aspects of numerical models separately.An adjustable Deardorff constant in the SGS model cμ = 0.25 and an amplitude of artificial viscosity in the gas-kinetic BGK scheme C2 = 0 are appropriate for the current study.We also calculated the density-weighted auto-and cross-correlation functions in Xiong’s turbulent stellar convection theory based on which the gradient type of models of the non-local transport and the anisotropy of the turbulence were preliminarily studied.No universal relations or con-stant parameters were found for these models.更多还原