/*---------------------------------------------------------------------------*\
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                    \\     ||  | Multiphase Code Repository by HZDR
  ======   //   ||  || ===//   | Website: https://doi.org/10.14278/rodare.767
  ||  ||  //    ||  // || \\   | License: GPL-3.0-or-later
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License
    This file is part of the Multiphase Code Repository by HZDR.

    Copyright (C) 2025 by Helmholtz-Zentrum Dresden-Rossendorf e.V. (HZDR),
    Website: https://hzdr.de

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Class
    Foam::surfaceTensionForceModels::smoothedContinuumSurfaceForce

Description
    Smoothing alpha fields prior to calculating the gradient vector of a phase
    pair to get interface curvature helps to dampen spurious currents. A number
    of two smoothing iterations show the least spurious currents.

    Reference:
    \verbatim
        Ubbink, O. (1997).
        Numerical prediction of two fluid systems with sharp interfaces.
        PhD Thesis, 193 pp. Imperial College of Science, Technology & Medicine
        London.
    \endverbatim

Usage
    \table
        Name         | Description                        | Default
        nSmoothIters | Number of iterations for smoothing | 2
    \endtable

SourceFiles
    smoothedContinuumSurfaceForce.C

\*---------------------------------------------------------------------------*/

#ifndef smoothedContinuumSurfaceForce_H
#define smoothedContinuumSurfaceForce_H

#include "continuumSurfaceForce.H"

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

namespace Foam
{
namespace surfaceTensionForceModels
{

/*---------------------------------------------------------------------------*\
                    Class smoothedContinuumSurfaceForce Declaration
\*---------------------------------------------------------------------------*/

class smoothedContinuumSurfaceForce
:
    public continuumSurfaceForce
{
    // Private Data

        //- Number of times to smoothen field
        const label nSmoothIters_;


    // Private Member Functions

        //- Smoothen a volScalarField for defined number of times
        tmp<volScalarField> smoothen(const volScalarField& vsf) const;


public:

    //- Runtime type information
    TypeName("smoothedContinuumSurfaceForce");


    // Constructors

        //- Construct from resolvedInterfaceSystem
        smoothedContinuumSurfaceForce
        (
            const resolvedInterfaceSystem& resolvedInterface,
            const bool registerObject
        );


    //- Destructor
    virtual ~smoothedContinuumSurfaceForce();


    // Member Functions

        //- Return the curvature of this interface
        virtual tmp<volScalarField> K
        (
            const segregatedPhaseInterface& interface
        ) const;
};


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

} // End namespace surfaceTensionForceModels
} // End namespace Foam

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

#endif

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