[maguirre]

Hi foamers!

During a parallel simulation, I encounter an issue with a custom boundary condition in OpenFOAM. The boundary condition is applied to a patch (plasmaSurf) and works fine in serial runs. However, in parallel, the simulation crashes with errors related to field sizes and bad memory allocation.

Key Details:

• The plasmaSurf patch has zero faces on some processors after decomposition.
• Errors include messages like:
  • size 0 is not equal to the given value of X (on processors with nFaces = 0)
  • bad size -Y (on processors with nFaces != 0)

What I've Tried:

• Verified the mesh with checkMesh -parallel (result is OK).
• Checked plasmaSurf in the processorX directories—confirmed it has zero faces on some processors.
• Simplified the boundary condition logic only to set value or gradient, but the issue persists in parallel runs.
• Switched to a simpler boundary condition (e.g., fixedValue) as a temporary fix, which works fine in parallel.
• Ensured decomposePar produces an evenly balanced decomposition and checked for mesh consistency.

Suspected Cause: The problem seems related to how the codedMixed boundary condition handles patches with zero faces in parallel. This might be a bug in my implementation or an inconsistency in how OpenFOAM distributes the patch data.

Question: How can I ensure the codedMixed boundary condition is robust to parallel runs where a patch might have zero faces on some processors? Are there best practices for handling such scenarios, or modifications needed to the codedMixed code to avoid these issues?

Code Implemented:

plasmaSurf
{
  type            codedMixed;
  namedummy_code;
  refValue        uniform 300;
  refGradient     uniform 0;
  valueFraction   uniform 0;
  
  code
  #{
    if (this->patch().size() == 0) // No faces on this processor
    {
      return;
    }
    scalarField& refGrad = this->refGrad();
    scalarField& refVal = this->refValue();
    scalarField& valueFraction = this->valueFraction();

    // Initialize to zero or default values
    refGrad = scalarField(patch().size(), 0.0);
    refVal = scalarField(patch().size(), 300.0);
    valueFraction = scalarField(patch().size(), 0.0);
  #};
}

(that code does not work even if the code block is empty)

Typical Error:

[1]
[1]
[1] --> FOAM FATAL IO ERROR:
[1] size 0 is not equal to the given value of -1871300200
[1]
[1] file: IStringStream.sourceFile from line 0 to line 4.
[1]
[1]     From function Foam::Field<Type>::Field(const Foam::word&, const Foam::dictionary&, Foam::label) [with Type = double; Foam::label = int]
[1]     in file /home/ubuntu/OpenFOAM/OpenFOAM-11/src/OpenFOAM/lnInclude/Field.C at line 208.
[1]
FOAM parallel run exiting
[1]
[0]
[0]
[0] --> FOAM FATAL ERROR:
[0] bad size -534376040
[0]
[0]     From function void Foam::List<T>::setSize(Foam::label) [with T = double; Foam::label = int]
[0]     in file /home/ubuntu/OpenFOAM/OpenFOAM-11/src/OpenFOAM/lnInclude/List.C at line 285.
[0]
FOAM parallel run aborting
[0]
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 1 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  Foam::error::printStack(Foam::Ostream&)

Any insights or suggestions would be greatly appreciated!