cellModel.C

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2017,2025 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
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    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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#include "cellModel.H"
#include "pyramid.H"
 
// * * * * * * * * * * * * * * * Local Functions * * * * * * * * * * * * * * //
 
namespace Foam
{
 
// Average of points
// Note: use double precision to avoid overflows when summing
static inline Foam::doubleVector pointsAverage
(
    const UList<point>& points,
    const labelUList& pointLabels
)
{
    doubleVector avg(Zero);
 
    if (const auto n = pointLabels.size(); n)
    {
        for (const auto pointi : pointLabels)
        {
            avg += points[pointi];
        }
        avg /= n;
    }
 
    return avg;
}
 
} // End namespace Foam
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
Foam::vector Foam::cellModel::centre
(
    const labelUList& pointLabels,
    const UList<point>& points
) const
{
    // Note: use double precision to avoid overflows when summing
 
    // Estimated centre by averaging the cell points
    const point centrePoint(pointsAverage(points, pointLabels));
 
 
    // Calculate the centre by breaking the cell into pyramids and
    // volume-weighted averaging their centres
 
    doubleScalar sumV(0);
    doubleVector sumVc(Zero);
 
    forAll(faces_, facei)
    {
        const Foam::face f(pointLabels, faces_[facei]);
 
        const scalar pyrVol = pyramidPointFaceRef(f, centrePoint).mag(points);
 
        if (pyrVol > SMALL)
        {
            WarningInFunction
                << "zero or negative pyramid volume: " << -pyrVol
                << " for face " << facei
                << endl;
        }
 
        sumV -= pyrVol;
        sumVc -= pyrVol * pyramidPointFaceRef(f, centrePoint).centre(points);
    }
 
    return sumVc/(sumV + VSMALL);
}
 
 
Foam::scalar Foam::cellModel::mag
(
    const labelUList& pointLabels,
    const UList<point>& points
) const
{
    // Note: use double precision to avoid overflows when summing
 
    // Estimated centre by averaging the cell points
    const point centrePoint(pointsAverage(points, pointLabels));
 
 
    // Calculate the magnitude by summing the -mags of the pyramids
    // The sign change is because the faces point outwards
    // and a pyramid is constructed from an inward pointing face
    // and the base centre-apex vector
 
    scalar sumV(0);
 
    forAll(faces_, facei)
    {
        const Foam::face f(pointLabels, faces_[facei]);
 
        const scalar pyrVol = pyramidPointFaceRef(f, centrePoint).mag(points);
 
        if (pyrVol > SMALL)
        {
            WarningInFunction
                << "zero or negative pyramid volume: " << -pyrVol
                << " for face " << facei
                << endl;
        }
 
        sumV -= pyrVol;
    }
 
    return sumV;
}
 
 
// ************************************************************************* //