Quickstart

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(c) 2019-2024 UCHICAGO ARGONNE, LLC
Build Status License

nekRS is a fast and scalable computational fluid dynamics (CFD) solver targeting HPC applications. The code started as an early fork of libParanumal in 2019, with the intention of supplanting its precursor, nek5000.

Capabilities:

  • Incompressible and low Mach-number Navier-Stokes + scalar transport

  • High-order curvilinear conformal Hex spectral elements in space

  • Variable time step 2nd/3rd order semi-implicit time integration

  • MPI + OCCA supporting CUDA, HIP, DPC++, SERIAL (C++)

  • LES and RANS turbulence models

  • Arbitrary-Lagrangian-Eulerian moving mesh

  • Lagrangian phase model

  • Overlapping overset grids

  • Conjugate fluid-solid heat transfer

  • Various boundary conditions

  • VisIt & Paraview for data analysis and visualization including in-situ support through Ascent

  • Legacy interface

Build Instructions

Requirements:

  • Linux, Mac OS X (Microsoft WSL and Windows is not supported)

  • GNU/oneAPI/NVHPC/ROCm compilers (C++17/C99 compatible)

  • MPI-3.1 or later

  • CMake version 3.21 or later

Download the latest release available under

https://github.com/Nek5000/nekRS/archive/refs/tags/v24.0.tar.gz

or clone our GitHub repository:

https://github.com/Nek5000/nekRS.git

The master branch always points to the latest stable release while next provides an early preview of the next upcoming release (do not use in a production environment).

If you’re on an HPC system, ensure you log in to a compute node. Check if there’s an nrsqsub script in the scripts directory for your system and load the same modules. Now, just run:

CC=mpicc CXX=mpic++ FC=mpif77 ./build.sh [-DCMAKE_INSTALL_PREFIX=$HOME/.local/nekrs] [<options>]

Adjust the compilers as necessary. Make sure to remove the previous build and installation directory if updating.

Setting the Environment

Assuming you run bash and your install directory is $HOME/.local/nekrs, add the following line to your $HOME/.bash_profile:

export NEKRS_HOME=$HOME/.local/nekrs
export PATH=$NEKRS_HOME/bin:$PATH

then type source $HOME/.bash_profile in the current terminal window.

Run the Code

We try hard not to break userland but the code is evolving quickly so things might change from one version to another without being backward compatible. Please consult RELEASE.md before using the code.

cd <directory outside of installation/source folder>
cp -a $NEKRS_HOME/examples/turbPipePeriodic .
mpirun -np 2 nekrs --setup turbPipe.par

For convenience we provide various launch scripts in the bin directory.

Documentation

For documentation, see our readthedocs page. For now it’s just a dummy. We recognize the importance of having comprehensive documentation to support our users. Creating such documentation requires initiative and collaboration and we hope to improve it soon.

The manual pages for the par file and environment variables can be accessed through nrsman

Discussion Group

Please visit GitHub Discussions. Here we help, find solutions, share ideas, and follow discussions.

Contributing

Our project is hosted on GitHub. To learn how to contribute, see CONTRIBUTING.md.

Reporting Bugs

All bugs are reported and tracked through Issues. If you are having trouble installing the code or getting your case to run properly, you should first visit our discussion group.

License

nekRS is released under the BSD 3-clause license (see LICENSE file). All new contributions must be made under the BSD 3-clause license.

Citing

If you find our project useful, please cite NekRS, a GPU-Accelerated Spectral Element Navier-Stokes Solver

Acknowledgment

This research was supported by the Exascale Computing Project (17-SC-20-SC), a joint project of the U.S. Department of Energy’s Office of Science and National Nuclear Security Administration, responsible for delivering a capable exascale ecosystem, including software, applications, and hardware technology, to support the nation’s exascale computing imperative.