[rangure]

hi,
I'm trying to identify the amount of water passing a plane. to achieve this, I add a functionObject in my controlDict. the function added is shown below. The case is a simpler version of damBreak, which is some water dropping from the air(see attachment).

functions
{
    flux
    {
        functionObjectLibs ("libfieldFunctionObjects.so");
        type             surfaceFieldValue;

        enabled          true;
        writeControl     outputTime;
        writeInterval    1;
        writeFields      true;

        name myName;
        surfaceFormat   none;
        // regionType: patch/faceZone/sampledSurface
        regionType sampledSurface;

        sampledSurfaceDict
        {
            type                  plane;
            planeType             pointAndNormal;
            pointAndNormalDict
            {
                point  (0.1 0 25);
                normal (0 0 1);
            };
            interpolate false;
        }

        // Operation: areaAverage/sum/weightedAverage/...
        operation    areaNormalIntegrate;
        fields
        (
            U
        );
    }
}

the problem is, when I run the simulation with interFoam, it generated a single file like this. but when I use

interFoam -postProcess

it generate a file for each tilmestep with different values. for example, at time 0.05, the value is

# Region type : sampledSurface myName
# Faces  :    178
# Area   :    8.900000e+00
# Time          areaNormalIntegrate(U)
0.05            (1.601638e+00 0.000000e+00 0.000000e+00)

here's the single file.

# Region type : sampledSurface myName
# Faces  :    184
# Area   :    9.200000e+00
# Time          areaNormalIntegrate(U)
0               (0.000000e+00 0.000000e+00 0.000000e+00)
0.05            (-2.227504e-04 0.000000e+00 0.000000e+00)
0.1             (-2.932480e-04 0.000000e+00 0.000000e+00)
0.15            (-8.891989e-05 0.000000e+00 0.000000e+00)
0.2             (-1.824714e-03 0.000000e+00 0.000000e+00)
0.25            (-3.951143e-05 0.000000e+00 0.000000e+00)
0.3             (-8.158129e-04 0.000000e+00 0.000000e+00)
0.35            (7.823114e-04 0.000000e+00 0.000000e+00)
0.4             (2.245233e-03 0.000000e+00 0.000000e+00)
0.45            (4.049318e-03 0.000000e+00 0.000000e+00)
0.5             (4.898588e-03 0.000000e+00 0.000000e+00)
0.55            (5.109302e-03 0.000000e+00 0.000000e+00)
0.6             (5.978782e-03 0.000000e+00 0.000000e+00)
0.65            (6.250927e-03 0.000000e+00 0.000000e+00)
0.7             (-2.399643e-03 0.000000e+00 0.000000e+00)
0.75            (-1.127230e-02 0.000000e+00 0.000000e+00)
0.8             (-7.155068e-03 0.000000e+00 0.000000e+00)
0.85            (-1.574159e-01 0.000000e+00 0.000000e+00)
0.9             (1.621918e-01 0.000000e+00 0.000000e+00)
0.95            (-1.254870e-01 0.000000e+00 0.000000e+00)
1               (3.400532e-02 0.000000e+00 0.000000e+00)
1.05            (7.201005e-02 0.000000e+00 0.000000e+00)
1.1             (9.076889e-02 0.000000e+00 0.000000e+00)
1.15            (-2.786471e-01 0.000000e+00 0.000000e+00)
1.2             (-5.048007e-01 0.000000e+00 0.000000e+00)
1.25            (-3.681236e-01 0.000000e+00 0.000000e+00)
1.3             (-5.155362e-01 0.000000e+00 0.000000e+00)
1.35            (-6.984839e-01 0.000000e+00 0.000000e+00)
1.4             (9.784959e-03 0.000000e+00 0.000000e+00)
1.45            (3.927942e-01 0.000000e+00 0.000000e+00)
1.5             (-3.542411e-01 0.000000e+00 0.000000e+00)
1.55            (-2.586261e+00 0.000000e+00 0.000000e+00)
1.6             (-6.864394e+00 0.000000e+00 0.000000e+00)
1.65            (-2.605651e-01 0.000000e+00 0.000000e+00)
1.7             (4.457992e+00 0.000000e+00 0.000000e+00)
1.75            (-3.350072e+00 0.000000e+00 0.000000e+00)
1.8             (-1.535838e+00 0.000000e+00 0.000000e+00)
1.85            (-3.504160e+00 0.000000e+00 0.000000e+00)
1.9             (-9.405926e+00 0.000000e+00 0.000000e+00)
1.95            (-1.448530e+01 0.000000e+00 0.000000e+00)
2               (8.364064e+00 0.000000e+00 0.000000e+00)
2.05            (7.780693e-01 0.000000e+00 0.000000e+00)
2.1             (-2.933097e+00 0.000000e+00 0.000000e+00)
2.15            (-6.424189e+00 0.000000e+00 0.000000e+00)
2.2             (-2.183912e+00 0.000000e+00 0.000000e+00)
2.25            (-6.395861e+00 0.000000e+00 0.000000e+00)
2.3             (-3.685619e+00 0.000000e+00 0.000000e+00)
2.35            (-4.437925e+00 0.000000e+00 0.000000e+00)
2.4             (-1.785322e+00 0.000000e+00 0.000000e+00)
2.45            (4.933389e+00 0.000000e+00 0.000000e+00)
2.5             (4.853685e+00 0.000000e+00 0.000000e+00)
2.55            (-2.499341e+00 0.000000e+00 0.000000e+00)
2.6             (-4.315828e+00 0.000000e+00 0.000000e+00)
2.65            (-1.217215e+01 0.000000e+00 0.000000e+00)
2.7             (-5.688268e+00 0.000000e+00 0.000000e+00)
2.75            (-3.997427e+00 0.000000e+00 0.000000e+00)
2.8             (-2.372049e+00 0.000000e+00 0.000000e+00)
2.85            (-7.069010e+00 0.000000e+00 0.000000e+00)
2.9             (-6.452742e+00 0.000000e+00 0.000000e+00)
2.95            (-1.762354e+00 0.000000e+00 0.000000e+00)
3               (-1.288960e+00 0.000000e+00 0.000000e+00)

I understand that the function is not correctly calculating the water volume, but it should gives same result for CLI execution and solver execution.