LeastSquaresGrad.C

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    Copyright (C) 2013-2016 OpenFOAM Foundation
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
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    under the terms of the GNU General Public License as published by
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
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#include "LeastSquaresGrad.H"
#include "LeastSquaresVectors.H"
#include "gaussGrad.H"
#include "fvMesh.H"
#include "volMesh.H"
#include "extrapolatedCalculatedFvPatchField.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
template<class Type, class Stencil>
Foam::tmp
<
    Foam::GeometricField
    <
        typename Foam::outerProduct<Foam::vector, Type>::type,
        Foam::fvPatchField,
    Foam::volMesh
    >
>
Foam::fv::LeastSquaresGrad<Type, Stencil>::calcGrad
(
    const GeometricField<Type, fvPatchField, volMesh>& vtf,
    const word& name
) const
{
    typedef typename outerProduct<vector, Type>::type GradType;
 
    const fvMesh& mesh = vtf.mesh();
 
    // Get reference to least square vectors
    const LeastSquaresVectors<Stencil>& lsv = LeastSquaresVectors<Stencil>::New
    (
        mesh
    );
 
    tmp<GeometricField<GradType, fvPatchField, volMesh>> tlsGrad
    (
        new GeometricField<GradType, fvPatchField, volMesh>
        (
            IOobject
            (
                name,
                vtf.instance(),
                mesh,
                IOobject::NO_READ,
                IOobject::NO_WRITE
            ),
            mesh,
            dimensioned<GradType>(vtf.dimensions()/dimLength, Zero),
            extrapolatedCalculatedFvPatchField<GradType>::typeName
        )
    );
    GeometricField<GradType, fvPatchField, volMesh>& lsGrad = tlsGrad.ref();
    Field<GradType>& lsGradIf = lsGrad;
 
    const extendedCentredCellToCellStencil& stencil = lsv.stencil();
    const List<List<label>>& stencilAddr = stencil.stencil();
    const List<List<vector>>& lsvs = lsv.vectors();
 
    // Construct flat version of vtf
    // including all values referred to by the stencil
    List<Type> flatVtf(stencil.map().constructSize(), Zero);
 
    // Insert internal values
    forAll(vtf, celli)
    {
        flatVtf[celli] = vtf[celli];
    }
 
    // Insert boundary values
    forAll(vtf.boundaryField(), patchi)
    {
        const fvPatchField<Type>& ptf = vtf.boundaryField()[patchi];
 
        label nCompact =
            ptf.patch().start()
          - mesh.nInternalFaces()
          + mesh.nCells();
 
        forAll(ptf, i)
        {
            flatVtf[nCompact++] = ptf[i];
        }
    }
 
    // Do all swapping to complete flatVtf
    stencil.map().distribute(flatVtf);
 
    // Accumulate the cell-centred gradient from the
    // weighted least-squares vectors and the flattened field values
    forAll(stencilAddr, celli)
    {
        const labelList& compactCells = stencilAddr[celli];
        const List<vector>& lsvc = lsvs[celli];
 
        forAll(compactCells, i)
        {
            lsGradIf[celli] += lsvc[i]*flatVtf[compactCells[i]];
        }
    }
 
    // Correct the boundary conditions
    lsGrad.correctBoundaryConditions();
    gaussGrad<Type>::correctBoundaryConditions(vtf, lsGrad);
 
    return tlsGrad;
}
 
 
// ************************************************************************* //