SWEEP
=====

An extension of the SPRAI radiative transfer module which shares the radiation chemistry implementation of 
SPRAI, but uses a different algorithm for the radiative transfer. The method employs transport sweeps which 
solve the scattering-less RTE in a single pass through the grid (per direction). This method is particularly 
suited for simulations with predominantly optically thin media.


Usage
-----

SWEEP can be used as a drop-in replacement for SPRAI. To do so, enable the ``SWEEP`` config parameter.


Additional Parameters
---------------------

* ``SweepConvergenceThreshold``
  In runs with periodic boundaries and/or scattering: The relative error at which the iterative solver will stop.

* ``SweepMaxNumIterations``
  The maximum number of iterations to perform in the iterative solver for scattering and/or periodic boundary conditions.


Additional Config.sh Options
----------------------------

SWEEP
  Master switch. Use SWEEP instead of SPRAI.

SWEEP_PERIODIC
  Run sweep with periodic boundaries. Then requires the ``SweepConvergenceThreshold`` and 
  ``SweepMaxNumIterations`` parameters.

SWEEP_SCATTER
  Run sweep with scattering. Then requires the ``SweepConvergenceThreshold`` and 
  ``SweepMaxNumIterations`` parameters.


Authors
-------

  * Toni Peter (toni.peter@uni-heidelberg.de)


Usage Policy and Citation
-------------------------

Please contact the authors before using this code, so that we can avoid any unnecessary project overlap. 
Co-authorship on independent publications produced with the code are not necessary, although we are happy 
to actively collaborate with users of the code that are interested in doing so.

Papers to cite:

  * `The Sweep method for radiative transfer in Arepo <https://arxiv.org/abs/2207.12848>`_