Neko is a portable framework for high-order spectral element flow simulations. Written in modern Fortran, Neko adopts an object-oriented approach, allowing multi-tier abstractions of the solver stack and facilitating various hardware backends ranging from general-purpose processors, CUDA and HIP enabled accelerators to SX-Aurora vector processors. Neko has its roots in the spectral element code Nek5000 from UChicago/ANL, from where many of the namings, code structure and numerical methods are adopted.

Neko is currently maintained and developed at KTH Royal Institute of Technology.

git clone https://github.com/ExtremeFLOW/neko

To build the project you will need: A Fortran compiler supporting the Fortran-08 standard, a working MPI installation, JSON-Fortran, and BLAS/lapack. Optional dependencies are gslib and ParMETIS. We use automake to build the project. These instructions should work in general, but as the project is quickly developing, things might change.

cd neko
./regen.sh
./configure --prefix=/path/to/neko_install --with-pfunit=/path/to/pFUnit/installed/PFUNIT-VERSION
make install

More detailed installation instructions can be found in the documentation.

After the project has been built

cd examples/tgv
/path/to/neko_install/bin/makeneko tgv.f90
mpirun -np 4 ./neko tgv.case

Assuming you configured with pFUnit you should be able to test the code with

make check

Documentation for Neko is available at https://neko.cfd/docs.

To generate the documentation, you need to have both doxygen and dot (part of the Graphviz package) installed (they will be picked up by configure). Once installed, you should be able to generate the documentation with

make html

• Jansson, N., 2021. Spectral Element Simulations on the NEC SX-Aurora TSUBASA. In proc. HPCAsia 2021.
• Karp, M., Podobas, A., Kenter, T., Jansson, N., Plessl, C., Schlatter, P. and Markidis, S., 2022. A high-fidelity flow solver for unstructured meshes on field-programmable gate arrays: Design, evaluation, and future challenges. In proc. HPCAsia 2022.
• Karp, M., Jansson, N., Podobas, A., Schlatter, P., and Markidis, S., 2022. Reducing Communication in the Conjugate Gradient Method: A Case Study on High-Order Finite Elements. In proc. PASC 2022.
• Karp, M., Massaro, D., Jansson, N., Hart, A., Wahlgren, J., Schlatter, P., and Markidis, S., 2023. Large-Scale Direct Numerical Simulations of Turbulence Using GPUs and Modern Fortran. The International Journal of High Performance Computing Applications, 37, 5.
• Jansson, N., Karp, M., Perez, A., Mukha, T., Ju, Y., Liu, J., Páll, S., Laure, E., Weinkauf, T., Schumacher, J., Schlatter, P., Markidis, S., 2023. Exploring the Ultimate Regime of Turbulent Rayleigh–Bénard Convection Through Unprecedented Spectral-Element Simulations. SC '23: Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis.
• Jansson, N., Karp, M., Podobas, A., Markidis, S. and Schlatter, P., 2024. Neko: A modern, portable, and scalable framework for high-fidelity computational fluid dynamics. Computer & Fluids, 275.

The development of Neko was supported by the European Commission Horizon 2020 project grant EPiGRAM-HS: Exascale Programming Models for Heterogeneous Systems (grant reference 801039), the Swedish Research Council project grant Efficient Algorithms for Exascale Computational Fluid Dynamics (grant reference 2019-04723) and the SeRC Exascale Simulation Software Initiative (SESSI). The Neko logo was designed by Robert Hansen Jagrelius.

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