Running in parallel: Number of cores

[akshathadixith]

I am running AdditiveFOAM simulations on a HPC. I specified one node and 24 cores in my SLURM submission file. But the simulation still runs using 6 cores. How do I change the number of cores? Do I specify it in the decomposeParDict file?

[colemanjs]

There a two steps to running AdditiveFOAM simulations on multiple cores:

1. You need to change the numberOfSubdomains in system/decomposeParDict to 24 (here)
2. You need to update corresponding mpirun so that the number of tasks is equal to the number of subdomains. For SLURM, this would be:

srun -N 1 -n 24 additiveFoam -parallel

Finally, before you run the application, don't forget to decompose the mesh again if you are changing the number of processors, using

decomposePar -force