# The TORUS radiation transfer code

## TL;DR

TORUS is a versatile radiation transfer and hydrodynamics code employing adaptive mesh refinement and Monte Carlo methods, capable of simulating complex astrophysical phenomena like star formation and stellar winds.

## Contribution

The paper provides a comprehensive review of the TORUS code's features, modules, validation, and diverse astrophysical applications, highlighting its flexibility and performance.

## Key findings

- Validated through benchmarking and scaling tests.
- Applied successfully to star formation and stellar wind simulations.
- Provides a flexible framework for synthetic observations.

## Abstract

We present a review of the TORUS radiation transfer and hydrodynamics code. TORUS uses a 1-D, 2-D or3-D adaptive mesh refinement scheme to store and manipulate the state variables, and solves the equation of radiative transfer using Monte Carlo techniques. A framework of microphysics modules is described, including atomic and molecular line transport in moving media, dust radiative equilibrium, photoionisation equilibrium, and time-dependent radiative transfer. These modules provide a flexible scheme for producing synthetic observations, either from analytical models or as post-processing of hydrodynamical simulations (both grid-based and Lagrangian). A hydrodynamics module is also presented, which maybe used in combination with the radiation-transport modules to perform radiation-hydrodynamics simulations. Benchmarking and validation tests of each major mode of operation are detailed, along with descriptions and performance/scaling tests of the various parallelisation schemes. We give examples of the uses of the code in the literature, including applications to low- and high-mass star formation, cluster feedback, and stellar winds, along with an Appendix listing the refereed papers that have used TORUS.