Problem with parallelization and a constant field located at constant folder
 

Hi Foamers,

I have the following problem: I am solving MHD with mhdFoam for a cylinder with an external constant magnetic field. I had to modify the solver to take in account this external and constant field. The idea was to split up B in one part fixed in time BFixed(r) and other variable in time and space BVble(r,t). As BFixed is the same every time step, I located it in constant folder. Otherwise it would be writing the same file always in every time directory.

The solver works good but the problem is when I want to divide the work in several subdomains. I wrote decomposePar, foamJob mpirun -np 2 cylinderMhdFoam -parallel &. But, the BFixed is not parallelized for some reason:
Any idea?

Thanks in advance :)

The problem of the parallelization with a field located in constant folder cannot be solved (easely at least). So I found out a solution much simpler: just make the solver read the field located at time folder 0 every time step. This has the same result.

Hi !

I am not sure to understand what are you saying. I have got the same issue as the solver needs to read a field located in the constant folder which is not included when I decomposed the case. How do you force the solver to read this field ?

Cheers.

Hello, I am adapting an immiscible two-phase flow solver for porous media for my own case. The solver runs fine in series but not in parallel.

Solver compilation and preliminary steps do not show any errors. Also, no error appears on "stepFields" or "decomposePar". The error appears when running the solver in parallel (please see below).

I believe the error has to do with the permeability "K" (constant cell-centered scalar field) being in the "constant" folder. When I run "decomposePar" the application does not decompose the permeability "K" in the processors.

Any feedback you could give me will be very appreciated.

Thank you very much for your attention and all the very best.

Sebastian


Reading porosity field eps (if present)

Reading permeability field K
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 3 in communicator MPI COMMUNICATOR 3 SPLIT FROM 0
with errorcode 1.

NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
You may or may not see output from other processes, depending on
exactly when Open MPI kills them.
--------------------------------------------------------------------------

--------------------------------------------------------------------------
[0]
[0]
[0] --> FOAM FATAL ERROR:
[0] cannot find file "/home/lopezsaa/OpenFOAM/lopezsaa-8/run/porousMultiphaseFoam-openfoam-v8/tutorials/lcl-tutorials/two_phase/paSaBCAnisob5PARALLEL/processor0/constant/K"
[0]
[0] From function virtual Foam::autoPtr<Foam::ISstream> Foam::fileOperations::uncollatedFileOperation::rea dStream(Foam::regIOobject&, const Foam::fileName&, const Foam::word&, bool) const
[0] in file global/fileOperations/uncollatedFileOperation/uncollatedFileOperation.C at line 538.
[0]
FOAM parallel run exiting
[0]
[1]
[1]
[1] --> FOAM FATAL ERROR:
[1] cannot find file "/home/lopezsaa/OpenFOAM/lopezsaa-8/run/porousMultiphaseFoam-openfoam-v8/tutorials/lcl-tutorials/two_phase/paSaBCAnisob5PARALLEL/processor1/constant/K"
[1]
[1] From function virtual Foam::autoPtr<Foam::ISstream> Foam::fileOperations::uncollatedFileOperation::rea dStream(Foam::regIOobject&, const Foam::fileName&, const Foam::word&, bool) const
[1] in file global/fileOperations/uncollatedFileOperation/uncollatedFileOperation.C at line 538.
[1]
FOAM parallel run exiting
[1]
[2]
[2]
[2] --> FOAM FATAL ERROR:
[2] cannot find file "/home/lopezsaa/OpenFOAM/lopezsaa-8/run/porousMultiphaseFoam-openfoam-v8/tutorials/lcl-tutorials/two_phase/paSaBCAnisob5PARALLEL/processor2/constant/K"
[2]
[2] From function virtual Foam::autoPtr<Foam::ISstream> Foam::fileOperations::uncollatedFileOperation::rea dStream(Foam::regIOobject&, const Foam::fileName&, const Foam::word&, bool) const
[2] in file global/fileOperations/uncollatedFileOperation/uncollatedFileOperation.C at line 538.
[2]
FOAM parallel run exiting
[2]
[3]
[3]
[3] --> FOAM FATAL ERROR:
[3] cannot find file "/home/lopezsaa/OpenFOAM/lopezsaa-8/run/porousMultiphaseFoam-openfoam-v8/tutorials/lcl-tutorials/two_phase/paSaBCAnisob5PARALLEL/processor3/constant/K"
[3]
[3] From function virtual Foam::autoPtr<Foam::ISstream> Foam::fileOperations::uncollatedFileOperation::rea dStream(Foam::regIOobject&, const Foam::fileName&, const Foam::word&, bool) const
[3] in file global/fileOperations/uncollatedFileOperation/uncollatedFileOperation.C at line 538.
[3]
FOAM parallel run exiting
[3]

did you modify anything in the solver code?
how do you create this K from the solverside?
volScalarField K ( IOobject -> from where does it read? ...

more input is required ...

Hello geth03.

After consulting experts I was able to solve the problem.

The problem was that the volScalarField K was being read from the "constant" folder. I learned that one shouldn't read fields from the constant solver - they belong into the time directory, which is decomposed.

So just had to modify the "createFields.H" file from this:


to this:


After that I recompiled the solver. Ran "decomposePar", ran in parallel and finally ran "reconstructPar" to visualize in paraview.

Thanks a lot for offering help!

no problem,

i assumed that K was taken from the constant folder,
that is why i asked how you read it and instantiate it.

anyway, glad you solved it already.

> runTime.constant(),

what if

> runTime.monkey(),

What does this line of code really do?