nekRS

nekRS is an open-source Navier Stokes solver based on the spectral element method targeting classical processors and hardware accelerators like GPUs. The code started as an early fork of libParanumal tailored to our needs. For portable programming OCCA is used.

Capabilities:

Incompressible and low Mach-number Navier-Stokes + scalar transport
CG-SEM using curvilinear conformal hexaheadral elements
3rd/2nd order semi-implicit time integration + operator integration factor splitting
MPI+X hybrid parallelism supporting CUDA, HIP, OPENCL and CPU
Interface to Nek5000
Conjugate fluid-solid heat transfer
LES and RANS turbulence models
ALE formulation for moving mesh support
VisIt & Paraview support for data analysis and visualization

Note, the code is an early state so it's very likely that you run into undiscovered issues. Moreover it's evolving quickly so things might change from one version to another without being backward compatible.

Build Instructions

Requirements:

POSIX compilant OS
GNU compiler collection version 6.2 or later
MPI-3.1 or later
CMake version 3.11 or later
bash

Download the latest release tarball (recommended)

wget https://github.com/Nek5000/nekRS/archive/refs/tags/v21.0.tar.gz 
tar -zxf v21.0.tar.gz

or clone our GitHub repository:

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

To build and install the code just run:

./makenrs

Build settings can be customized in the script.

Setting the Enviroment

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 Example

cd $NEKRS_HOME/examples/turbPipePeriodic
nrspre turbPipe 2 # precompile JIT code
nrsmpi turbPipe 2 # run on two MPI ranks

You may have to adjust the example launch scripts nrsmpi/nrsbmpi to your environment. Please check the examples in bin.

Documentation

For documentation, see our readthedocs page.

Discussion Group

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

Reporting Bugs

nekRS is hosted on GitHub and all bugs are reported and tracked through the Issues feature. If you are having trouble installing the code or getting your model to run properly, you should first vist our discussion group.

Contributing

Our project is hosted on GitHub and everbody is welcome to become a part of it. For more details see CONTRIBUTING.md.

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.

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.

liujiamingustc / nekRS