EDP Sciences
Free access
Volume 501, Number 2, July II 2009
Page(s) 813 - 820
Section Numerical methods and codes
DOI http://dx.doi.org/10.1051/0004-6361/200911793
Published online 13 May 2009
A&A 501, 813-820 (2009)
DOI: 10.1051/0004-6361/200911793

Comoving-frame radiative transfer in arbitrary velocity fields

II. Large scale applications
S. Knop1, P. H. Hauschildt1, and E. Baron1, 2, 3

1  Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
    e-mail: [sknop;yeti]@hs.uni-hamburg.de
2  Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks, Rm 100, Norman, OK 73019, USA
    e-mail: baron@ou.edu
3  Computational Research Division, Lawrence Berkeley National Laboratory, MS 50F-1650, 1 Cyclotron Rd, Berkeley, CA 94720, USA

Received 4 February 2009 / Accepted 18 March 2009

Aims. A solution of the radiative-transfer problem in arbitrary velocity fields introduced in a previous paper, has limitations in its applicability. For large-scale applications, the methods described also require large memory sets that are commonly not available to state-of-the-art computing hardware. In this work, we modify the algorithm to allow the computation of large-scale problems.
Methods. We reduce the memory footprint via a domain decomposition. By introducing iterative Gauss-Seidel type solvers, we improve the speed of the overall computation. Because of the domain decomposition, the new algorithm requires the use of parallel-computing systems.
Results. The algorithm that we present permits large-scale solutions of radiative-transfer problems that include arbitrary wavelength couplings. In addition, we discover a quasi-analytic formal solution of the radiative transfer that significantly improves the overall computation speed. More importantly, this method ensures that our algorithm can be applied to multi-dimensional Lagrangian radiative-transfer calculations. In multi-dimensional atmospheres, velocity fields are in general chaotic ensuring that the inclusion of arbitrary wavelength couplings are mandatory.

Key words: radiative transfer

© ESO 2009