GALÆXI is a GPGPU-enabled extension of FLEXI, a high-order numerical framework for solving PDEs, with a special focus on Computational Fluid Dynamics. GALÆXI is based on the Discontinuous Galerkin Spectral Element Method (DGSEM), which allows for high-order of accuracy and fully unstructured hexahedral meshes. The solver is parallelized very efficiently for large-scale applications using MPI-aware CUDA Fortran and has demonstrated excellent scaling on over 1000 NVIDIA GPUs. Moreover, GALÆXI comes with a capable pre- and postprocessing suite that enables complex simulation setups up to the finished visualization.
GALÆXI has been developed by the Numerics Research Group (NRG) founded by Prof. Claus-Dieter Munz and currently lead by Prof. Andrea Beck at the Institute of Aerodynamics and Gasdynamics at the University of Stuttgart, Germany.
You can find detailed installation instructions, extensive documentation and several tutorial cases for GALÆXI here.
GALÆXI is Copyright (C) 2016, Prof. Claus-Dieter Munz and is released under the GNU General Public License v3.0. For the full license terms see the included license file.
Numerous people have worked on and with GALÆXI over the last years. We would like to thank all these contributors for their efforts they spent on building GALÆXI.
In case you have questions regarding GALÆXI or want to contribute yourself by either reporting bugs, requesting features or adding somthing different to the project, feel free to open an issue or pull request.
GALÆXI is a scientific project. If you use GALÆXI for publications or presentations in science, please support the project by citing it. As general reference, please cite
Kurz, M., Kempf, D., Blind, M. P., Kopper, P., Offenhäuser, P., Schwarz, A., Starr, S., Keim, J., Beck, A. (2025).
GALÆXI: Solving complex compressible flows with high-order discontinuous Galerkin methods on accelerator-based systems,
Computer Physics Communications, 306, 109388.
or use the following Bibtex files
@article{galaexi,
title = {GAL{\AE}XI: Solving complex compressible flows with high-order discontinuous Galerkin methods on accelerator-based systems},
journal = {Computer Physics Communications},
volume = {306},
pages = {109388},
year = {2025},
author = {Marius Kurz and Daniel Kempf and Marcel P. Blind and Patrick Kopper and Philipp Offenhäuser and Anna Schwarz and Spencer Starr and Jens Keim and Andrea Beck},
url = {https://www.sciencedirect.com/science/article/pii/S0010465524003114},
doi = {https://doi.org/10.1016/j.cpc.2024.109388},
note = {Code available at \url{https://github.com/flexi-framework/galaexi}.}
}
To refer to specific applications and features, you can also cite the appropriate paper from this list.
For a more detailed installation instructions, please see the documention here.
GALÆXI is tested for various Linux distributions including Ubuntu, OpenSUSE, CentOS and Arch. It currenly only supports offloading to NVIDIA GPUs. Also, compilation is currently only possible with the NVIDIA HPC SDK compilers (nvfortran). For installation you require the following dependencies:
| Package | Required | Installed by GALÆXI |
|---|---|---|
| Git | x | |
| CMake | x | |
| C/C++ Compiler | x | |
| Fortran Compiler | x | |
| LAPACK | x | x |
| HDF5 | x | x |
| MPI | (x) | |
| CUDA | x |
The MPI library is only required for running parallel simulations on multiple ranks and the HDF5 and LAPACK libraries can be installed automatically during the GALÆXI build process. The names of the packages and the package manager might differ depending on the specific distribution used.
Open a terminal, download GALÆXI via git and optionally export the GALÆXI directory:
git clone https://github.com/flexi-framework/galaexi.git
export GALAEXI_DIR="$(pwd)/galaexi"
Enter the GALÆXI directory, create a build directory and use CMake to configure and compile the code
cd $GALAEXI_DIR
mkdir build; cd build
cmake ../
make
The executable galaexi is now contained in the GALÆXI directory in build/bin/.
Custom configurations of the compiler options, dependencies and code features can be set using
ccmake ../
Navigate to the directory of the tutorial naca0012 and run GALÆXI
cd $GALAEXI_DIR/tutorials/naca0012
$GALAEXI_DIR/build/bin/galaexi parameter_flexi_navierstokes.ini
GALÆXI uses several external libraries as well as auxiliary functions from open source projects, including: