Turbulent convection in stars

Abstract

This thesis investigates in detail the structure of models of turbulent convec tion with phenomenological closures for the eddy-viscosity. It explores the merits of replacing the canonical Mixing Length Theory of stellar convection with more realistic models of fluid turbulence that take into account the full spectrum of eddy sizes. The author provides a detailed exposition of the fun damental assumptions and the modus operandi of various approaches to the treatment of convective energy-transfer in stars. He focuses in particular on spectral descriptions of the convective process. The structure of several clo sure models developed by various authors are investigated, and he identifies and elucidates those aspects of these closures that lead to an improved descrip tion of convective turbulence in the stellar interior. The author also develops an implementation within the public-domain code, called Modules for Experi ments in Stellar Astrophysics, of two of these models and reports and discusses the results of his numerical experiments.