CFD Online Discussion Forums - [swak4Foam] Trouble accessing fields within expressionField

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[swak4Foam] Trouble accessing fields within expressionField

Hello all,

I am trying to use swak4foam to calculate a velocity field (based on position in the mesh), and this works great! But then I try to add that velocity field to the UMean field calculate by OpenFOAM 2.4.0, using the following controlDict entry:

Code:

    UCalc

    {

        after  $monStart;

        type expressionField;

        outputControlMode  outputTime;

        outputInterval     $endTime;

        fieldName UCalc;

        dimension [ 0 1 -1 0 0 0 0 ];

        expression "UMean + Urot";

        autowrite true;

    }

This gives the following errors:

Code:

Creating expression field Urot ... type:volVectorField

[13]

[13]

[13] --> FOAM FATAL ERROR:

[13]  Parser Error for driver FieldValueExpressionDriver at "1.1-5" :"field UMean not existing or of wrong type"

"UMean + Urot"

  ^^^^^

--|    



Context of the error:





- Driver constructed from scratch

  Evaluating expression "UMean + Urot"

[13]

[13]

[13]     From function parsingValue

[13]     in file lnInclude/CommonValueExpressionDriverI.H at line 1189.

[13]

FOAM parallel run exiting

I am bit confused what is going wrong, as UMean definitely exists for all timesteps. Perhaps I need to load UMean within the controlDict entry, before swak4foam has access to it? Any ideas?

Quick questions:

Where and how did you define "UMean"?
And is it "UMean" or "Umean"?

Quote:

Originally Posted by wyldckat (Post 583134)

Quick questions:

Where and how did you define "UMean"?
And is it "UMean" or "Umean"?

Thanks for the reply. UMean is created by the open foam function object fieldAverage.

Quick answer: Sorry, but only today did I managed to come back to your problem.

OK, I believe that the problem is because you need to use a function object that loads the field after it's saved. For example:

Code:

readFields

{

    // Where to load it from (if not already in solver)

    functionObjectLibs ("libfieldFunctionObjects.so");



    type            readFields;

    fields          (UMean);

}

You will need to add this before the function object you provided.

The other solution is to use swak4Foam's own function object for calculating the "UMean" field.

Quote:

Originally Posted by wyldckat (Post 586178)

Code:

readFields

{

    // Where to load it from (if not already in solver)

    functionObjectLibs ("libfieldFunctionObjects.so");



    type            readFields;

    fields          (UMean);

}

You will need to add this before the function object you provided.

The other solution is to use swak4Foam's own function object for calculating the "UMean" field.

I was hoping that this would fix my problem as well, but it did not for either OF 2.3 or 3.0 :(

Here is what I am working with:

Code:

...

functions

{

    cubeUx

    {

        type expressionField;

        dimension [0 3 -3 0 0 0 0];

        fieldName "cubeUx";

        expression "pow(U.x,3)";

        verbose true;

        autowrite false;

        outputControl timeStep;

    }

    

    fieldAverage1

    {

        type            fieldAverage;

        functionObjectLibs ( "libfieldFunctionObjects.so" );

        enabled         true;

        outputControl   outputTime;



        fields

        (

            U

            {

                mean        on;

                prime2Mean  on;

                base        time;

            }



            p

            {

                mean        on;

                prime2Mean  on;

                base        time;

            }



            cubeUx

            {

                mean on;

                prime2Mean off;

                base time;

            }

        );

    }



    readFields

    {

        functionObjectLibs  ("libfieldFunctionObjects.so");

        type        readFields;

        fields      (cubeUxMean);

    }



    skewnessX

    {

        type expressionField;

        dimension [0 3 -3 0 0 0 0];

        fieldName "skewnessX";

        expression "(cubeUxMean-3*UMean.x*UPrime2Mean.xx-pow(UMean.x,3))/pow(UPrime2Mean.xx,1.5)";

        verbose true;

        autowrite true;

        outputControl timeStep;

    }

}



libs (

    "libOpenFOAM.so"

    "libsimpleFunctionObjects.so"

    "libsimpleSwakFunctionObjects.so"

    "libswakFunctionObjects.so"

    );

Hi,

rigth now I have the same problem. readFields and also reading the Field with the solver does not solve that in OpenFOAM 4.1 :mad:

Quote:

Originally Posted by david112 (Post 648657)

Hi,

rigth now I have the same problem. readFields and also reading the Field with the solver does not solve that in OpenFOAM 4.1 :mad:

Tiam addresses this issue here:
https://www.cfd-online.com/Forums/op...tml#post616247