Turbulence modeling of solar convection

Numerical simulations are performed of a highly unstable stratified turbulent flow field, which represents the upper part of the convection zone in the Sun. Plasma and magnetic fields, known as solar winds, propagate out from the solar atmosphere. These solar winds are highly dependant upon the activity in the convection zone. The simulations performed are a time dependent, three-dimensional and physically realistic models. The turbulent flow field is modeled by large-eddy simulation (LES) to obtain detailed information regarding the solar convection zone. In LES, the large length-scales are resolved, while the small scales are modeled by a sub-grid scale (SGS) model. To capture the correct physics, realistic SGS models are needed. Many SGS models have been investigated and reported in the literature, but their performance in highly stratified flows are unknown. Currently, no adequate SGS models exist for highly stratified flows. The aim of this investigation is to investigate the performance of two SGS models that are commonly used in isotropic turbulence: the Smagorinsky model (SM), and the mixed model (MM). The SM is an eddy-viscosity based model, and the MM is a linear combination between SM and the scale-similarity model (SSM). The effect from the two SGS models on the results is compared. The results from this investigation are compared to data previously reported in the literature.