A CLASS OF PHYSICALLY MOTIVATED CLOSURES FOR RADIATION HYDRODYNAMICS

Journal Article · Tue Feb 01 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/727/2/67· OSTI ID:21567575

Chan, Chi-kwan ^[1]

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1. Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

Radiative transfer and radiation hydrodynamics use the relativistic Boltzmann equation to describe the kinetics of photons. It is difficult to solve the six-dimensional time-dependent transfer equation unless the problem is highly symmetric or in equilibrium. When the radiation field is smooth, it is natural to take angular moments of the transfer equation to reduce the degrees of freedom. However, low order moment equations contain terms that depend on higher order moments. To close the system of moment equations, approximations are made to truncate this hierarchy. Popular closures used in astrophysics include flux-limited diffusion and the M{sub 1} closure, which are rather ad hoc and do not necessarily capture the correct physics. In this paper, we propose a new class of closures for radiative transfer and radiation hydrodynamics. We start from a different perspective and highlight the consistency of a fully relativistic formalism. We present a generic framework to approximate radiative transfer based on relativistic Grad's moment method. We then derive a 14-field method that minimizes unphysical photon self-interaction.

• OSTI ID: 21567575
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 727; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
BOLTZMANN EQUATION
BOSONS
CALCULATION METHODS
DIFFERENTIAL EQUATIONS
ELEMENTARY PARTICLES
ENERGY TRANSFER
EQUATIONS
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
INTEGRO-DIFFERENTIAL EQUATIONS
KINETIC EQUATIONS
KINETICS
MASSLESS PARTICLES
MECHANICS
MOMENTS METHOD
PARTIAL DIFFERENTIAL EQUATIONS
PHOTONS
RADIANT HEAT TRANSFER
TIME DEPENDENCE