Volume 599, March 2017
|Number of page(s)||12|
|Section||Numerical methods and codes|
|Published online||10 March 2017|
Numerical non-LTE 3D radiative transfer using a multigrid method
Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Centre, 106 91 Stockholm, Sweden
Received: 13 December 2016
Accepted: 4 January 2017
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(n2), 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.
Key words: radiative transfer / Sun: chromosphere / methods: numerical
© ESO, 2017
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.