Angularly adaptive –double flux-limited diffusion solutions of non-equilibrium grey radiative transfer problems
✍ Scribed by Patrick S. Brantley
- Book ID
- 104028389
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 436 KB
- Volume
- 104
- Category
- Article
- ISSN
- 0022-4073
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✦ Synopsis
The double spherical harmonics angular approximation in the lowest order, i.e. double P 0 (DP 0 ), is developed for the solution of time-dependent non-equilibrium grey radiative transfer problems in planar geometry. Although the DP 0 diffusion approximation is expected to be less accurate than the P 1 diffusion approximation at and near thermodynamic equilibrium, the DP 0 angular approximation can more accurately capture the complicated angular dependence near a nonequilibrium radiation wave front. In addition, the DP 0 approximation should be more accurate in non-equilibrium optically thin regions where the positive and negative angular domains are largely decoupled. We develop an adaptive angular technique that locally uses either the DP 0 or P 1 flux-limited diffusion approximation depending on the degree to which the radiation and material fields are in thermodynamic equilibrium. Numerical results are presented for two test problems due to Su and Olson and to Ganapol and Pomraning for which semi-analytic transport solutions exist. These numerical results demonstrate that the adaptive P 1 -DP 0 diffusion approximation can yield improvements in accuracy over the standard P 1 diffusion approximation, both without and with flux-limiting, for non-equilibrium grey radiative transfer.