Morphology of convection and mixing-length theory

Abstract

It is pointed out that observations and numerical experiments are not the only way to determine the morphological characteristics of convection in different layer of stars. It is demonstrated that a sufficiently general formulation of mixing length theory (MLT) that incorporates the kinetic energy flux and the anisotropy of turbulence can be used to give reliable predictions concerning the morphology. Such an MLT, applied to a recent model of the solar convective zone (SCZ), shows that the morphology in the bulk of the SCZ is characterized by isolated fibrillar downflows. A topology reversal occurs a few hundred km below the photosphere, and the outer layers are characterized by isolated upflows and a cellular structure. If the SCZ has a thin lower boundary layer, then near it the structure becomes cellular again, but with isolated downflows. Unlike solar-type stars, convective stellar cores are probably not dominated by fibrillar isolated downflows, but rather by isolated upflows.