An iterative phasespace explicit discontinuous Galerkin method for stellar radiative transfer in extended atmospheres
Abstract
In this work, a phasespace discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inversepowerlaw scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusivetransparent transition region, and the forward peaking behavior at the surface of extended atmospheres were accurately captured. The integrodifferential equation of radiation transfer is solved iteratively by alternating between the radiative pressure equation and the original equation with the integral term treated as an energy density source term. In each iteration, the equations are solved via an explicit, fluxconserving, discontinuous Galerkin method. Finite elements are ordered in wave fronts perpendicular to the characteristic curves so that elemental linear algebraic systems are solved quickly by sweeping the phase space element by element. Two implementations of a diffusive boundary condition at the origin are demonstrated wherein the finite discontinuity in the radiation intensity is accurately captured by the proposed method. This allows for a consistent mechanism to preserve photon luminosity. The method was proved tomore »
 Authors:

 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Separations Group, Chemical Sciences Division
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC21)
 OSTI Identifier:
 1357999
 Alternate Identifier(s):
 OSTI ID: 1413855
 Grant/Contract Number:
 AC0500OR22725
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Journal of Quantitative Spectroscopy and Radiative Transfer
 Additional Journal Information:
 Journal Volume: 196; Journal Issue: C; Journal ID: ISSN 00224073
 Publisher:
 Elsevier
 Country of Publication:
 United States
 Language:
 English
 Subject:
 97 MATHEMATICS AND COMPUTING; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Citation Formats
de Almeida, Valmor F. An iterative phasespace explicit discontinuous Galerkin method for stellar radiative transfer in extended atmospheres. United States: N. p., 2017.
Web. doi:10.1016/j.jqsrt.2017.04.007.
de Almeida, Valmor F. An iterative phasespace explicit discontinuous Galerkin method for stellar radiative transfer in extended atmospheres. United States. doi:10.1016/j.jqsrt.2017.04.007.
de Almeida, Valmor F. Wed .
"An iterative phasespace explicit discontinuous Galerkin method for stellar radiative transfer in extended atmospheres". United States. doi:10.1016/j.jqsrt.2017.04.007. https://www.osti.gov/servlets/purl/1357999.
@article{osti_1357999,
title = {An iterative phasespace explicit discontinuous Galerkin method for stellar radiative transfer in extended atmospheres},
author = {de Almeida, Valmor F.},
abstractNote = {In this work, a phasespace discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inversepowerlaw scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusivetransparent transition region, and the forward peaking behavior at the surface of extended atmospheres were accurately captured. The integrodifferential equation of radiation transfer is solved iteratively by alternating between the radiative pressure equation and the original equation with the integral term treated as an energy density source term. In each iteration, the equations are solved via an explicit, fluxconserving, discontinuous Galerkin method. Finite elements are ordered in wave fronts perpendicular to the characteristic curves so that elemental linear algebraic systems are solved quickly by sweeping the phase space element by element. Two implementations of a diffusive boundary condition at the origin are demonstrated wherein the finite discontinuity in the radiation intensity is accurately captured by the proposed method. This allows for a consistent mechanism to preserve photon luminosity. The method was proved to be robust and fast, and a case is made for the adequacy of parallel processing. In addition to classical twodimensional plots, results of normalized radiation intensity were mapped onto a logpolar surface exhibiting all distinguishing features of the problem studied.},
doi = {10.1016/j.jqsrt.2017.04.007},
journal = {Journal of Quantitative Spectroscopy and Radiative Transfer},
number = C,
volume = 196,
place = {United States},
year = {2017},
month = {4}
}