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An adaptive mesh, astrophysical radiation hydrodynamics simulation code
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an adaptive mesh, astrophysical radiation hydrodynamics simulation code

Castro is an adaptive-mesh compressible radiation hydrodynamics code for astrophysical flows. Castro supports a general equation of state, full Poisson gravity, and reactive flows, and is parallelized with MPI + OpenMP.

More information on Castro can be found here:

Getting Started

You can download Castro and all the necessary dependencies (AMReX and the Microphysics repo) using the script:

Running this will clone the repositories and create a file which you can source or copy to your .bashrc to define the necessary environment variables.

The User's Guide in written in re-structured text using Sphinx, with the source in Castro/sphinx_docs/, and is built automatically via travis from the development branch. You can find the online guide at:

The Getting Started section should guide you through your first run.

Call Graph

A doxygen-generated call graph for Castro is available here:

Development Model:

Development generally follows the following ideas:

  • New features are committed to the development branch.

    Nightly regression testing is used to ensure that no answers change (or if they do, that the changes were expected).

    If a change is critical, we can cherry-pick the commit from development to master.

  • Contributions are welcomed from anyone. Any contributions that have the potential to change answers should be done via pull requests. A pull request should be generated from your fork of Castro and target the development branch. (If you mistakenly target master, we can change it for you.)

    Please add a line to CHANGES summarizing your change if it is a bug fix or new feature. Reference the PR or issue as appropriate. Additionally, if your change fixes a bug (or if you find a bug but do not fix it), and there is no current issue describing the bug, please file a separate issue describing the bug, regardless of how significant the bug is. If possible, in both the CHANGES file and the issue, please cite the pull request numbers or git commit hashes where the problem was introduced and fixed, respectively.

    If there are a number of small commits making up the PR, we may wish to squash commits upon merge to have a clean history. Please ensure that your PR title and first post are descriptive, since these will be used for a squashed commit message.

  • On the first workday of each month, we perform a merge of development into master, in coordination with AMReX, Maestro, and Microphysics. For this merge to take place, we need to be passing the regression tests.

    To accommodate this need, we close the merge window into development a few days before the merge day. While the merge window is closed, only bug fixes should be pushed into development. Once the merge from development -> master is done, the merge window reopens.

Core Developers

People who make a number of substantive contributions will be named "core developers" of Castro. The criteria for becoming a core developer are flexible, but generally involve one of the following:

  • 10 non-merge commits to Castro/Source/ or Castro/sphinx_docs/ or one of the problems that is not your own science problem or

  • addition of a new algorithm / module or

  • substantial input into the code design process or testing

Core developers will be recognized in the following ways:

  • invited to the group's slack team

  • listed in the User's Guide and website as a core developer

  • listed in the author list on the Zenodo DOI for the project (as given in the .zenodo.json file)

  • invited to co-author general code papers / proceedings describing Castro, its performance, etc. (Note: science papers will always be left to the science leads to determine authorship).

If a core developer is inactive for 3 years, we may reassess their status as a core developer.

Mailing list

You can subscribe to the castro-help mailing list at google groups:!forum/castro-help

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