Plumes in Stellar Convection Zones
All numerical simulations of compressible convection reveal the presence of strong downward directed flows. Thanks to helioseismology, such plumes have now also been detected at the top of the solar convection zone, on supergranular scales. Their properties may be crudely described by adopting Taylor's turbulent entrainment hypothesis, whose validity is well established under various conditions. Using this model, one finds that the strong density stratification does not prevent the plumes from traversing the whole convection zone, and that they carry upward a net energy flux. They penetrate to some extent in the adjacent stable region, where they establish an almost adiabatic stratification when there is little radiative diffusion. These plumes have a strong impact on the dynamics of stellar convection zones, and they probably play a key role in the dynamo mechanism.
convection turbulence hydrodynamics solar and stellar interiors