[CBranch171]

Hello

I have changed to openfoam 2212 and the behaviour of activePressureForceBaffleVelocity changes compared to 2206. For some reason I get a factor of 2 mutliplied for the force on both sides of the baffle. So now the pressure difference on the baffle is twice the 2206 version of the code. Yet I cannot see any difference between the files. Has anybody noticed this.

The code in both versions 2206 and 2212 have the same fix to correct division by 2 that was occurring due to the walls patch being 2 twice the area of the cyclic patches. But for some reason the force calculated now is 2x the size. This occurs for either side of the patch so the master pressure and the slave pressure are 2x what they are actually.

I can add a divide by 2 and the codes agree perfectly but I would like to know what has changed between the 2206 and 2212 versions to make this happen.

[CBranch171]

This is not due to openfoam versions. I have multiple activePressureForceBaffleVelocity BCs, 3 in total, and the way the current code calculates the pressure gave incorrect pressures on the BC after the first one. They were twice the actual pressures and hence twice the pressure difference.

I changed the code as follows and the error is removed:

scalar valueDiff = 0;
scalar force1 = 0;
scalar force2 = 0;
scalar press1 = 0;
scalar press2 = 0;
scalar area1 = 0;
scalar area2 = 0;

if (fBased_)
{
// Add this side
forAll(cyclicFaceCells, facei)
{
force1 +=p[cyclicFaceCells[facei]]*mag(initCyclicSf_[facei]);
}

// Remove other side
forAll(nbrFaceCells, facei)
{
force2 -=p[nbrFaceCells[facei]]*mag(initCyclicSf_[facei]);
}

reduce(valueDiff, sumOp<scalar>());
reduce(force1, sumOp<scalar>());
reduce(force2, sumOp<scalar>());

valueDiff = force1 - force2;

Info<< "Force difference = " << valueDiff << endl;
}
else // pressure based
{
forAll(cyclicFaceCells, facei)
{
force1 += p[cyclicFaceCells[facei]]*mag(initCyclicSf_[facei]);
area1 += mag(initCyclicSf_[facei]);
}

forAll(nbrFaceCells, facei)
{
force2 += p[nbrFaceCells[facei]]*mag(initCyclicSf_[facei]);
area2 += mag(initCyclicSf_[facei]);
}

reduce(valueDiff, sumOp<scalar>());
reduce(force1, sumOp<scalar>());
reduce(force2, sumOp<scalar>());
reduce(press1, sumOp<scalar>());
reduce(press2, sumOp<scalar>());
reduce(area1, sumOp<scalar>());
reduce(area2, sumOp<scalar>());

press1 = force1/area1;
press2 = force2/area2;
valueDiff = press1 - press2;

Info<< "Pressure difference = " << valueDiff << endl;
Info<< "p1 p2 = " << press1 << " " << press2 << endl;
}

It seems you cannot calculate the pressure average or pressure difference with the area that is not reduced. area1 and area2 are indeed the same but for consistency I have left it like the above.