NUCLEAR EXPLOSION INTERACTION STUDIES. VOLUME : METHODS FOR ANALYSIS OF RADIATIVE TRANSFER
Abstract
The non-equilibrium diffusion approximation to the radiative-transfer equation is developed. The first two moments of the radiative transfer equation, including Thomson scattering and pure absorption, are formed, and the equations are closed by a relation between the radiation energy and pressure. Applications of SPUTTER non-equilibrium diffusion subroutines to several simple radiative- transfer problems are described and compared with results from other numerical radiative-transfer codes. Subroutines are also described which calculate the effect of Thomson scattering in TAMALE. The method of moments, the method of discrete ordinates of characteristics, and the Monte Carlo method are described with special reference to the calculation of radiative transport in two dimensions. Their relative merits are discussed, and considerations bearing on the choice of which to use in various applications are given. The non- equilibrium diffusion approximation, which is the variant of the moments method used in DRADTN and ERADTN, has been extended to axially symmetric configurations of two dimensions in a new program, TDRAD. The method of characteristics has been programmed for the same geometry as that treated by TDRAD. The new code, TRAN2, extends TDRAD to situations in which the radiation is too anisotropic to be described by only two moments. The problem of averaging absorption coefficients and scattering cross sections is a basic one in any calculation of radiative transport. A proposed solution is formulated, and transmission functions are derived for the case where opacities may be considered piecewise constant in space and frequency.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1967
- Accession Number
- AD0815185
Entities
People
- C. R. Dismukes
- J. H. Alexander
- K. D. Pyatt Jr.
- R. Durstenfeld
- R. S. Engelmore
Organizations
- General Dynamics