[mcgoldba]

Hi All,

I would like to get a mean value of a field that is is calculated with a function object. However, this is resulting in a error, I think because the function object field is not initialized at the beginning of the simulation.

For simplicity I have recreated the error with a modified version of the channel935 case. My modified controlDict for this case is as follows:

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     pimpleFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         20;

deltaT          0.2;

writeControl    timeStep;

writeInterval   10;

purgeWrite      0;

writeFormat     ascii;

writePrecision  6;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

functions
{
    fieldAverage1
    {
        type            fieldAverage;
        libs            ("libfieldFunctionObjects.so");
        writeControl    writeTime;

        fields
        (
            U
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }

            p
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }
            dp
            {
                mean        on;
                prime2Mean  off;
                base        time;
            }
        );
    }

    gradU
    {
        type             grad;
        libs             ("libfieldFunctionObjects.so");
        field            p;
        result           dp;
        writeControl     writeTime;        
    }

}

// ************************************************************************* //

I receive the following error after the second time step

[0] --> FOAM FATAL ERROR:
[0]
    request for volVectorField dpMean from objectRegistry region0 failed
    available objects of type volVectorField are
5
(
U_0
U
UMean
U_0_0
dp
)
[0]
[0]
[0]     From function const Type& Foam::objectRegistry::lookupObject(const Foam::word&) const [with Type = Foam::
    GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>]
[0]     in file /home/ubuntu/OpenFOAM/OpenFOAM-7/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 193.
[0]
FOAM parallel run aborting

Can anyone help with the correct implementation to get the averaged field?

[Yann]

Hi Marc,

Have you tried switching the two functions, i.e. calculating dp first, then doing the fieldAverage ?

Yann

[mcgoldba]

That indeed was the issue. Thank you for the suggestion!

Everything is calculated correctly if I revise the controlDict function order to the following:

functions
{

    gradp
    {
        type             grad;
        libs             ("libfieldFunctionObjects.so");
        field            p;
        result           dp;
        writeControl     writeTime;        
    }
    
    fieldAverage1
    {
        type            fieldAverage;
        libs            ("libfieldFunctionObjects.so");
        writeControl    writeTime;
        //timeStart       4;       

        fields
        (
            U
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }

            p
            {
                mean        on;
                prime2Mean  on;
                base        time;
            }
            dp
            {
                mean        on;
                prime2Mean  off;
                base        time;
            }
        );
    }


}