filteredLinear3.H

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License
    This file is part of OpenFOAM.
 
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    the Free Software Foundation, either version 3 of the License, or
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Class
    Foam::filteredLinear3Limiter
 
Description
    Class to generate weighting factors for the filteredLinear
    interpolation scheme.
 
    The aim is to remove high-frequency modes with "staggering"
    characteristics by comparing the face gradient with both neighbouring
    cell gradients and introduce small amounts of upwind in order to damp
    these modes.
 
    Used in conjunction with the template class LimitedScheme.
 
SourceFiles
    filteredLinear3.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef filteredLinear3_H
#define filteredLinear3_H
 
#include "vector.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
/*---------------------------------------------------------------------------*\
                   Class filteredLinear3Limiter Declaration
\*---------------------------------------------------------------------------*/
 
template<class LimiterFunc>
class filteredLinear3Limiter
:
    public LimiterFunc
{
    // Private Data
 
        // Scaling coefficient for the gradient ratio,
        // 0 = linear
        // 1 = fully limited
        scalar k_;
 
public:
 
    filteredLinear3Limiter(Istream& is)
    :
        k_(readScalar(is))
    {
        if (k_ < 0 || k_ > 1)
        {
            FatalIOErrorInFunction(is)
                << "coefficient = " << k_
                << " should be >= 0 and <= 1"
                << exit(FatalIOError);
        }
    }
 
    scalar limiter
    (
        const scalar cdWeight,
        const scalar faceFlux,
        const typename LimiterFunc::phiType& phiP,
        const typename LimiterFunc::phiType& phiN,
        const typename LimiterFunc::gradPhiType& gradcP,
        const typename LimiterFunc::gradPhiType& gradcN,
        const vector& d
    ) const
    {
        // Difference across face
        scalar df = phiN - phiP;
 
        // Twice the differences across face-neighbour cells
        scalar dP = 2*(d & gradcP);
        scalar dN = 2*(d & gradcN);
 
        // Calculate the limiter
        scalar limiter = 1 - k_*(dN - df)*(dP - df)/max(sqr(dN + dP), small);
 
        // Limit the limiter between linear and upwind
        return max(min(limiter, 1), 0);
    }
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //