Thesis (Ph.D.)--Cornell University, 1981.
|Statement||by Joel Mirick MacAuslan.|
The simplest parametrization of sub-grid scales (SGS) consists in modeling their effects as enhanced viscosity and heat diffusivity. This approach has the advantage of giving the modeler full control on the sub-grid scales model, but lacks a physical justification in the context of solar (and stellar) by: The goal has been to establish from basic physical principles a self-consistent description of convection represented by a group of equations with no ad hoc parameters. In this context, the most successful theory of stellar convection in the literature is the mixing-length theory (ML theory). In a laboratory fluid, the effective mixing length is usually found to equal the size of the convective region. In stellar models, where fluids are compressible, and convection can extend over many pressure (or density) scale heights, the mixing length is usually set equal to a fraction of the local pressure scale height. The review considers the modelling process for stellar convection rather than specific astrophysical results. For achieving reasonable depth and length we deal with hydrodynamics only, omitting MHD. A historically oriented introduction offers first glimpses on the physics of stellar by:
Stellar Convection Convection in Stellar Models Kim, Y.-C., and Demarque, P. , ApJ, , "The Theoretical Calculation of the` Rossby Number and the "Non-Local" Convective Overturn Time for Pre-Main Sequence and Early Post-Main Sequence Stars". Convection is a complicated topic and reamins an active area of research, in particular because it can have considerable impact on a wide range of stellar properties and stellar evolution. The lack of a good theory of convection, and the amount of energy which can be transfered by convection, is at present a limitation on our understanding of stellar structure. These include the description of stellar convection, the in- clusion of non-linear e ects in stellar pulsation, and the e ect of rapid rotation on the pulsation modes . Any formula used to calculate the temperature gradient in a stellar convection zone must be calibrated, for example, by evolving 1-solar-mass stellar models to fit the present age, luminosity, and.
carried by convection (and radiation) with an appropriate theory. Despite the great importance of convection in modelling the structure and evolution of a star, a satisfactory treat-ment of stellar convection is still open to debate and until now a self-consistent description of this important physical phenomenon has been by: 6. highly efficient convection maintains a nearly adiabatic stratification such that the integrated heat flux through the convection zone is small relative to the thermal energy of the plasma. In nature, thermal-energy transport may also occur through conduction (direct contact between a . It is worth noting that often "self-consistent equation" is a misuse for "self-consistency equation", namely an equation whose role is to guarantee the self consistency of a theory (model, whatever). If the equation is satisfied then the theory is self-consistent. Joel MacAuslan currently works at STAR Analytical Services. Joel does research in Applied Mathematics, Acoustics and Computing in Mathematics, Natural Science, Engineering and Medicine.