AMReX-Astro/Castro: Castro 20.03

We now depend on the fundamental constants from Microphysics instead of keep our own copy in Castro (#787)

We removed the ppm_predict_gammae option for the CTU hydro solver. This was not used frequently and did not show much difference with the default (rho e) reconstruction. (#780)

The Microphysics "extern" parameters are now available in C++

We've started converting the CTU hydro solver from Fortran to C++ (#731). The PPM reconstruction is now done in C++ (#784).

The option ppm_temp_fix = 3 was removed. This used a temperature-based eigensystem for characteristic tracing but was never used for production science.

If a derived variable has multiple components, all components are now added to plotfiles. Previously only the first component was used. (#758)

We have updated our workflow when it comes to Castro's dependencies.

Previously Castro shipped with it a minimal set of microphysics that allowed basic problem setups like Sedov to compile, and more advanced setups (like ones that include nuclear burning) required downloading the starkiller-astro Microphysics repository as an additional step. Now, that Microphysics repository is a requirement for using Castro. If you are a current user of the Microphysics repository and prefer the current workflow where you maintain Microphysics as a separate installation from Castro, no change in your workflow is necessary: if MICROPHYSICS_HOME is set as an environment variable, Castro will use the Microphysics installation in that directory. However we have also added Microphysics as a git submodule to Castro, which is now the required path if you previously were not using the more advanced microphysics (but is also a possibility for those previously using a standalone Microphysics installation). To obtain this, you can use git submodule update --init --recursive from the top-level directory of Castro. The developer team ensures that the version of Microphysics that you obtain this way is consistent with the current version of Castro. Then, you can keep up to date with the code mostly as normal, except now using git pull --recurse-submodules instead of git pull.

Similarly, AMReX is now maintained as a git submodule rather than as an external standalone installation. If you use the same git submodule command as above, you'll obtain AMReX. As with Microphysics, you may opt to rely on your own installation of AMReX by setting the AMREX_HOME environment variable. However you are then responsible for keeping it in sync with Castro; if you use the submodule, then you'll get the version of AMReX that we have tested to ensure compatibility with the current version of Castro. (#651, #760, #762, #765)

The names of the conserved state variables in C++ (Density, Xmom, etc.) have been changed to match the names in Fortran (URHO, UMX, etc.). For user code, this will only affect problem-specific setup code like Prob.cpp that references specific state variables. For compatibility, we have kept a copy of the old names around that redirect to the new names, but the old names are now considered deprecated and will be removed