Parallel Run

[sihaeri]

Hi,
Is there any tutorials showing how to set up a parallel run with this solver? I can run the tutorials on one core, however, the when trying a parallel run, the solver crash with Floating point exception errors.
Many thanks

[Renaud-Matthias]

Hello,

Currently, the implementation of the Exner equation does not support parallel computation. To run parallel simulations, the boundary patch corresponding to the sediment bed must be kept on a single processor. The simulation will fail at the first time iteration if the bed boundary is split between multiple processors.
Parallel simulations remain feasible through the use of a domain decomposition strategy that maintains the integrity of the bed patch. A solution is to add a file topoSetDict in your system folder with the following content:

actions
(
{
    name chtiot;  // can be any other name
    type faceSet;
    action new;
    source patchToFace;
    sourceInfo
    {
        patch bed;  // name of your sediment bed boundary
    }
}
);

Then, specify the following options in your decomposeParDict

constraints
{
    processors
    {
        type    singleProcessorFaceSets;
        sets    ((chtiot -1));
        enabled true;
    }
}

Do not forget to run the topoSet command before decomposePar. Also keep in mind that when using a very large computational domain, the decomposition constraints will eventually degrade model performance due to sub-optimal partitioning and excessive inter-processor communication.

I am keeping this issue open for now, since the present solution is still not optimal and will require further improvement.

Thank you for your interest,
Matthias