Overview

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.

For more information, please visit https://neko.cfd.

Note: The page may be changed until the competition stats, maybe sure to follow up until the opening ceremony.

Neko presentation to the teams:

Presentation file:

Building and Running example

Download Neko v0.8.0-rc1, https://github.com/ExtremeFLOW/neko/archive/refs/tags/v0.8.0-rc1.tar.gz.

To build Neko, you will need a Fortran compiler supporting the Fortran-08 standard, autotools, pkg-config, a working MPI installation supporting the Fortran 2008 bindings (mpi_f08), BLAS/LAPACK and JSON-Fortran. Detailed installation instructions can be found in the Neko manual.

Sample build script:

#!/bin/bash
export MPIFC=mpif90
export CC=mpicc
export FC=$MPIFC
export PKG_CONFIG_PATH=/path/to/jsonfortran/lib/pkgconfig:${PKG_CONFIG_PATH}

./regen.sh
./configure --prefix=<path>
make
make install

 Sample output: (Update)

    _  __  ____  __ __  ____
   / |/ / / __/ / //_/ / __ \
  /    / / _/  / ,<   / /_/ /
 /_/|_/ /___/ /_/|_|  \____/

 (version: 0.8.0-rc1)
 (build: 2024-04-10 on x86_64-pc-linux-gnu using cray)


 -------Job Information--------
 Start time: 10:41 / 2024-04-10
 Running on: 256 MPI ranks
 CPU type  : AMD EPYC 7742 64-Core Processor
 Bcknd type: CPU
 Real type : double precision

 -------------Case-------------
 Reading case file tgv_Re1600.case

   -------------Mesh-------------
   Reading a binary Neko file 32768.nmsh
...

   -----Material properties------
   Read non-dimensional values:
...
   -----Starting simulation------
...

   -----Starting simulation------
   T  : [  0.0000000E+00,  0.2000000E+01)
   dt :    0.5000000E-03
...
   ----------------------------------------------------------------
   t =   0.0000000E+00                                  [   0.00% ]
   ----------------------------------------------------------------
   Time-step:      1
    CFL:  0.3970812E-01 dt:  0.5000000E-03
...
   ----------------------------------------------------------------
   t =   0.2000000E+01                                  [ 100.00% ]
   ----------------------------------------------------------------
   Time-step:   4001
    CFL:  0.4271451E-01 dt:  0.5000000E-03
...
       --------Writer output---------
       File name: field.fld
       Output number:     10
       Writing at time:   2.000500 Output time (s):  2.501281
 Normal end.

GPU support:

To compile Neko with GPU support, please follow either the instructions in the manual (Compiling Neko for NVIDIA GPUs and Compiling Neko for AMD GPUs).

Note: A Neko installation can only support one backend. Thus, to run both CPU and GPU experiments, two different builds and installations are necessary.

Tasks & Submissions

These tasks aim to solve the given flow case as fast as possible (time to solution); this is reported as the Elapsed time in the log files and includes everything from solving the equations to performing I/O.

1. Run Neko with the given input (neko tgv_Re1600.case) on CPU nodes and submit the results to the team’s folder (standard output)
   Note: the small input is for you to play around.

2. Run Neko with the given input on a couple of GPUs (the memory requirements of the case is roughly 2 A100 or 4 V100) and submit the results to the team’s folder (see instructions for GPU support above, and the additional information provided with the input file)

Note: You are allowed to experiment with different linear solvers in Neko (see the manual) to achieve the fastest runtime. However, all of them are not guaranteed to work for the given case or support all hardware backends in Neko.