Supergranulation Scale Convection Simulations
Abstract
Results of realistic simulations of solar surface convection on the scale of supergranules (96 Mm wide by 20 Mm deep) are presented. The simulations cover only 10% of the geometric depth of the solar convection zone, but half its pressure scale heights. They include the hydrogen, first and most of the second helium ionization zones. The horizontal velocity spectrum is a power law and the horizontal size of the dominant convective cells increases with increasing depth. Convection is driven by buoyancy work which is largest close to the surface, but significant over the entire domain. Close to the surface buoyancy driving is balanced by the divergence of the kinetic energy flux, but deeper down it is balanced by dissipation. The damping length of the turbulent kinetic energy is 4 pressure scale heights. The mass mixing length is 1.8 scale heights. Two thirds of the area is upflowing fluid except very close to the surface. The internal (ionization) energy flux is the largest contributor to the convective flux for temperatures less than 40,000 K and the thermal energy flux is the largest contributor at higher temperatures.
 Publication:

15th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
 Pub Date:
 February 2009
 DOI:
 10.1063/1.3099227
 Bibcode:
 2009AIPC.1094..764S
 Keywords:

 96.60.Jw;
 47.57.Gc;
 02.60.x;
 Solar interior;
 Granular flow;
 Numerical approximation and analysis;
 fluid dynamics;
 granular flow;
 numerical analysis