Time-implicit compressible simulations of turbulent convection in the interior of a young sun
J. Pratt
University of Exeter
I. Baraffe, C. Geroux, T. Goffrey, M. Viallet, M.V. Popov, D. Folini, R. Walder
Current physical understanding of the evolution of stellar interiors is drawn from one-dimensional calculations, which efficiently allow astrophysicists to explore a wide range of stellar environments. In one-dimensional calculations, turbulent convection in stellar interiors is modelled using mixing length theory. Concrete understanding of the differences between mixing length theory, and 2 and 3-dimensional fluid convection under realistic stellar conditions could improve the quality and fit of models for one-dimensional stellar evolution codes, and could determine to what extent 2 dimensional simulations can be used predictively. With this motivation, we describe how the multi-dimensional, time implicit, fully compressible, hydrodynamical, implicit large eddy simulation code MUSIC has been designed to expand the results of a one dimensional stellar evolution calculation into a 2 or 3-dimensional fluid simulation. We use MUSIC to study an early stage in the evolution of a star that is convective from the central regions to the surface. We perform two- and three-dimensional simulations that include different physical sections of the star in the numerical domain. The effect of small-scale convection in the near surface layers on the fundamental characteristics of deep convection in the star is explored. Similarly, we examine how the dynamics of waves in the radiative zone can affect the fundamental characteristics of deep convection. These studies are preliminary to characterizing convective overshooting at the boundary between the radiative and convective zones.