OUprocess.C

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    This file is part of OpenFOAM.
 
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#include "OUprocess.H"
#include "Kmesh.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
complexVector OUprocess::WeinerProcess(const scalar deltaT) const
{
    return sqrt(deltaT)*complexVector
    (
        complex(stdNormal_.sample(), stdNormal_.sample()),
        complex(stdNormal_.sample(), stdNormal_.sample()),
        complex(stdNormal_.sample(), stdNormal_.sample())
    );
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
OUprocess::OUprocess
(
    const Kmesh& kmesh,
    const scalar deltaT,
    const dictionary& OUdict
)
:
    stdNormal_(0),
    Kmesh_(kmesh),
    OUfield_(Kmesh_.size()),
 
    alpha_(OUdict.lookup<scalar>("alpha")),
    sigma_(OUdict.lookup<scalar>("sigma")),
    kUpper_(OUdict.lookup<scalar>("kUpper")),
    kLower_(OUdict.lookup<scalar>("kLower")),
    scale_((kUpper_ - kLower_)*pow(scalar(Kmesh_.size()), 1.0/vector::dim))
{
    const vectorField& K = Kmesh_;
 
    scalar sqrkUpper_ = sqr(kUpper_);
    scalar sqrkLower_ = sqr(kLower_) + small;
    scalar sqrK;
 
    forAll(OUfield_, i)
    {
        if ((sqrK = magSqr(K[i])) < sqrkUpper_ && sqrK > sqrkLower_)
        {
            OUfield_[i] = scale_*sigma_*WeinerProcess(deltaT);
        }
        else
        {
            OUfield_[i] = complexVector
            (
                complex(0, 0),
                complex(0, 0),
                complex(0, 0)
            );
        }
    }
}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
const complexVectorField& OUprocess::newField(const scalar deltaT) const
{
    const vectorField& K = Kmesh_;
 
    scalar sqrkUpper_ = sqr(kUpper_);
    scalar sqrkLower_ = sqr(kLower_) + small;
    scalar sqrK;
 
    forAll(OUfield_, i)
    {
        if ((sqrK = magSqr(K[i])) < sqrkUpper_ && sqrK > sqrkLower_)
        {
            OUfield_[i] =
                (1.0 - alpha_*deltaT)*OUfield_[i]
              + scale_*sigma_*WeinerProcess(deltaT);
        }
    }
 
    return OUfield_;
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// ************************************************************************* //