[gigilentini8]

Dear FOAMers,
can you confirm me that the function object below in ControlDict is the correct and fastest way to calculate average over cutting planes in a 3D simulation during runtime?
it seems to work but I'm not 100% sure about the results...

functions
{
    cuttingplane_average
    {
        type            faceSource;
        functionObjectLibs ("libfieldFunctionObjects.so");

        enabled         true;
        outputControl   outputTime;

        // Output to log&file (true) or to file only
        log             true;

        // Output field values as well
        valueOutput     false;  //true;

        // Type of source: patch/faceZone/sampledSurface
        source          sampledSurface;

        sampledSurfaceDict
        {
                type cuttingPlane;
                planeType           pointAndNormal;
                pointAndNormalDict
                {
                        basePoint       (0 0 0);  
                        normalVector    (0 0 1);
                }
                source cells; // sample cells or boundaryFaces
                interpolate true;
        }

        // Operation: areaAverage/sum/weightedAverage ...
        operation       areaAverage;

        fields
        (
            p
            U
        );
    }

[fede32]

was it right?

[Vidal]

In OF version 7 I have managed to report on runtime the average value on a cutting plane by modifying a little the above code, which is inside the "functions" sub-dictionary in the controlDict:

cuttingplane_average
{
    type            surfaceFieldValue;
    libs            ("libfieldFunctionObjects.so");
    enabled         yes;
    writeControl    timeStep;
    writeInterval   1; 
    log             yes;
    // Output field values as well
    writeFields     no;
    // Type of source: patch/faceZone/sampledSurface
    regionType      sampledSurface;
    name            sampledSurfaceNormalZ1;
    sampledSurfaceDict
    {
            type                    cuttingPlane;
            planeType               pointAndNormal;
            pointAndNormalDict
            {
                    basePoint       (0 0 1);  
                    normalVector    (0 0 1);
            }
            source cells; // sample cells or boundaryFaces
            interpolate true;
    }
    // Operation: areaAverage/sum/weightedAverage ...
    operation       areaAverage;
    fields
    (
        U p
    );
}

The changes are:
1. "type" must be "surfaceFieldValue" instead of "faceSource".
2. It is necessary to give a user "name" for the average value output ("sampledSurfaceNormalZ1" in my case.)
3. Other differences are I guess because the different OF versions ("regionType" instead of "source", "writeControl", ...).

I hope it helps.

Cheers

[olesen]

For future reference as well: if you are using OpenFOAM-v1906 or later you also have the possibility to create/sample surfaces and "store" them. This places them in memory where they can be picked up later for surfaceFieldValue and/or runTimePostProcessing.


In many cases this can be more efficient and flexible than creating the sampled surfaces from within surfaceFieldValue itself.



https://develop.openfoam.com/Develop.../-/issues/1206


https://www.openfoam.com/documentati...s.html#details

[NotOverUnderated]

Originally Posted by olesen

For future reference as well: if you are using OpenFOAM-v1906 or later you also have the possibility to create/sample surfaces and "store" them. This places them in memory where they can be picked up later for surfaceFieldValue and/or runTimePostProcessing.


In many cases this can be more efficient and flexible than creating the sampled surfaces from within surfaceFieldValue itself.



https://develop.openfoam.com/Develop.../-/issues/1206


https://www.openfoam.com/documentati...s.html#details

Is it possible to use those stored surfaces with fieldAverage function object? I am looking for a way to average over time not space.

In a normal static case it would be easier to just compute the mean fields (e.g., UMean, pMean, etc) then using the surface sampling on those fields. Unfortunately this cannot be used with moving/sliding meshes because the computed mean fields using fieldAverage are wrong on the moving/sliding region.

I use meshSurface (obj file) to compute the surfaces sampling at each time but I have no idea how to average them over time (not space which can be easily handled by surfaceFieldValue).

Is there any solution to this?