Scalable matrix-free solver for 3D transfer of polarized radiation in stellar atmospheres

0572595 - ASÚ 2024 RIV NL eng J - Článek v odborném periodiku
Benedusi, P. - Riva, S. - Zulian, P. - Štěpán, Jiří - Belluzzi, L. - Krause, R.
Scalable matrix-free solver for 3D transfer of polarized radiation in stellar atmospheres.
Journal of Computational Physics. Roč. 479, April (2023), č. článku 112013. ISSN 0021-9991. E-ISSN 1090-2716
Grant CEP: GA ČR(CZ) GA19-20632S
Institucionální podpora: RVO:67985815
Klíčová slova: radiative transfer * polarization * scattering
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 4.1, rok: 2022
Způsob publikování: Open access

We present an efficient and massively parallel solution strategy for the transfer problem of polarized radiation, for a 3D stationary medium out of local thermodynamic equilibrium. Scattering processes are included accounting for partial frequency redistribution effects. Such a setting is one of the most challenging ones in radiative transfer modeling. The problem is formulated for a two-level atomic model, which allows linearization. The discrete ordinate method alongside an exponential integrator are used for discretization. Efficient solution is obtained with a Krylov method equipped with a tailored physics-based preconditioner. A matrix-free approach results in a lightweight implementation, suited for tackling large problems. Near-optimal strong and weak scalability are obtained with two complementary decompositions of the computational domain. The presented approach made it possible to perform simulations for the Ca I line at 4227 angstrom with more than 109 degrees of freedom in less than half an hour on massively parallel machines, always converging in a few iterations for the proposed tests. (c) 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/).
Trvalý link: https://hdl.handle.net/11104/0343834