UOprocess.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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    \\  /    A nd           | Copyright (C) 1991-2010 OpenCFD Ltd.
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#include <OpenFOAM/error.H>

#include "UOprocess.H"
#include <randomProcesses/Kmesh.H>
#include <OpenFOAM/dictionary.H>

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //

complexVector UOprocess::WeinerProcess()
{
    return RootDeltaT*complexVector
    (
        complex(GaussGen.GaussNormal(), GaussGen.GaussNormal()),
        complex(GaussGen.GaussNormal(), GaussGen.GaussNormal()),
        complex(GaussGen.GaussNormal(), GaussGen.GaussNormal())
    );
}


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

// from components
UOprocess::UOprocess
(
    const Kmesh& kmesh,
    const scalar deltaT,
    const dictionary& UOdict
)
:
    GaussGen(label(0)),
    Mesh(kmesh),
    DeltaT(deltaT),
    RootDeltaT(sqrt(DeltaT)),
    UOfield(Mesh.size()),

    Alpha(readScalar(UOdict.lookup("UOalpha"))),
    Sigma(readScalar(UOdict.lookup("UOsigma"))),
    Kupper(readScalar(UOdict.lookup("UOKupper"))),
    Klower(readScalar(UOdict.lookup("UOKlower"))),
    Scale((Kupper - Klower)*pow(scalar(Mesh.size()), 1.0/vector::dim))
{
    const vectorField& K = Mesh;

    scalar sqrKupper = sqr(Kupper);
    scalar sqrKlower = sqr(Klower) + SMALL;
    scalar sqrK;

    forAll(UOfield, i)
    {
        if ((sqrK = magSqr(K[i])) < sqrKupper && sqrK > sqrKlower)
        {
            UOfield[i] = Scale*Sigma*WeinerProcess();
        }
        else
        {
            UOfield[i] = complexVector
            (
                complex(0, 0),
                complex(0, 0),
                complex(0, 0)
            );
        }
    }
}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

const complexVectorField& UOprocess::newField()
{
    const vectorField& K = Mesh;

    label count = 0;
    scalar sqrKupper = sqr(Kupper);
    scalar sqrKlower = sqr(Klower) + SMALL;
    scalar sqrK;

    forAll(UOfield, i)
    {
        if ((sqrK = magSqr(K[i])) < sqrKupper && sqrK > sqrKlower)
        {
            count++;
            UOfield[i] =
                (1.0 - Alpha*DeltaT)*UOfield[i]
              + Scale*Sigma*WeinerProcess();
        }
    }

    Info<< "    Number of forced K = " << count << nl;

    return UOfield;
}


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

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