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Numerical non-LTE 3D radiative transfer using a multigrid method
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, Department of Astronomy.
Number of Authors: 2
2017 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 599, A118Article in journal (Refereed) Published
Abstract [en]

Context. 3D non-LTE radiative transfer problems are computationally demanding, and this sets limits on the size of the problems that can be solved. So far, multilevel accelerated lambda iteration (MALI) has been the method of choice to perform high-resolution computations in multidimensional problems. The disadvantage of MALI is that its computing time scales as O(n(2)), with n the number of grid points. When the grid becomes finer, the computational cost increases quadratically. Aims. We aim to develop a 3D non-LTE radiative transfer code that is more efficient than MALI. Methods. We implement a non-linear multigrid, fast approximation storage scheme, into the existing Multi3D radiative transfer code. We verify our multigrid implementation by comparing with MALI computations. We show that multigrid can be employed in realistic problems with snapshots from 3D radiative magnetohydrodynamics (MHD) simulations as input atmospheres. Results. With multigrid, we obtain a factor 3.3-4.5 speed-up compared to MALI. With full-multigrid, the speed-up increases to a factor 6. The speed-up is expected to increase for input atmospheres with more grid points and finer grid spacing. Conclusions. Solving 3D non-LTE radiative transfer problems using non-linear multigrid methods can be applied to realistic atmospheres with a substantial increase in speed.

Place, publisher, year, edition, pages
2017. Vol. 599, A118
Keyword [en]
radiative transfer, Sun: chromosphere, methods: numerical
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:su:diva-142717DOI: 10.1051/0004-6361/201630237ISI: 000395821900130OAI: oai:DiVA.org:su-142717DiVA: diva2:1092995
Available from: 2017-05-04 Created: 2017-05-04 Last updated: 2017-05-04Bibliographically approved

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Bjørgen, Johan P.Leenaarts, Jorrit
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CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf