Numerical simulations of mass outflows from star-forming regions

The development, testing, and application of a two dimensional radiation magnetohydrodynamics (RMHD) code is described in detail. Well developed Eulerian hydrodynamic algorithms are used, but are implemented in a new covariant formalism which facilitates simulations in any orthogonal coordinate system. The recently developed constrained transport (CT) algorithm is implemented for the numerical evolution of the components of a magnetic field for MHD simulations. This algorithm guarantees the numerical evolved field components will satisfy the divergence free constraint at all times. It is found, however, that in its original form the CT algorithm is unable to propagate all modes of the MHD wave families (in particular shear Alfven waves) stably. Therefore, an extension to the CT algorithm is developed using the method of characteristics (MOC), and it is demonstrated that the resulting hybrid CT/MOC method does provide for the stable evolution of all modes of MHD wave families. A two dimensional full transport algorithm to evolve the radiation moment equations is developed and tested for RHD simulations. The moment equations are closed with the tensor variable Eddington factor whose components are computed from angular quadratures of the specific intensity which, in turn, is computed from a formal solution of the two dimensional transfer equation using the method of short characteristics. This algorithm for multi-dimensional RHD differs significantly from more commonly used methods based on the diffusion approximation. Particular care is taken to test all the algorithms used in the code extensively. Detailed descriptions of the setup and results for each test problem used for the HD, MHD, and RHD algorithms is provided.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Astronomy

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Stone, James McLellan

Contributors dc:contributor

• Mihalas, Dimitri

• Physics, Astronomy and Astrophysics
• Physics, Radiation
• Physics, Fluid and Plasma

Statement dc:rights

• Copyright 1990 Stone, James McLellan

Language dc:language

eng

Identifier

AAI9114425
(UMI)AAI9114425

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20221