Lun.H

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    Copyright (C) 2013-2016 OpenFOAM Foundation
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
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Class
    Foam::ParticleStressModels::Lun
 
Group
    grpLagrangianIntermediateMPPICParticleStressSubModels
 
Description
    Inter-particle stress model of Lun et al
 
    The stress value takes the following form:
    \f[
        \left( \alpha \rho + \alpha^2 \rho (1 + e) \frac{3}{5}
        \left( 1 - \left( \frac{\alpha}{\alpha_{pack}} \right)^\frac{1}{3}
        \right) \right) \frac{1}{3} \sigma^2
    \f]
    Here, \f$\alpha\f$ is the volume fraction of the dispersed phase,
    \f$\rho\f$ is the density of the dispersed phase, \f$e\f$ is a coefficient
    of restitution, and \f$\sigma\f$ is the RMS velocity fluctuation.
 
    Reference:
    \verbatim
        "Kinetic theories for granular flow: inelastic particles in Couette
        flow and slightly inelastic particles in a general flowfield"
        C Lun, S Savage, G Jeffrey, N Chepurniy
        Journal of Fluid Mechanics
        Volume 140, Pages 223-256, 1984
    \endverbatim
 
SourceFiles
    Lun.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef Lun_H
#define Lun_H
 
#include "ParticleStressModel.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace ParticleStressModels
{
 
/*---------------------------------------------------------------------------*\
                        Class Lun Declaration
\*---------------------------------------------------------------------------*/
 
class Lun
:
    public ParticleStressModel
{
    // Private data
 
        //- Coefficient of restitution
        scalar e_;
 
        //- Smallest allowable difference from the packed volume fraction
        scalar eps_;
 
 
public:
 
    //- Runtime type information
    TypeName("Lun");
 
 
    //- Constructors
 
        //- Construct from components
        Lun(const dictionary& dict);
 
        //- Construct copy
        Lun(const Lun& hc);
 
        //- Clone
        virtual autoPtr<ParticleStressModel> clone() const
        {
            return autoPtr<ParticleStressModel>
            (
                new Lun(*this)
            );
        }
 
 
    //- Destructor
    virtual ~Lun();
 
 
    //- Member Functions
 
        //- Collision stress
        tmp<Field<scalar>> tau
        (
            const Field<scalar>& alpha,
            const Field<scalar>& rho,
            const Field<scalar>& uRms
        ) const;
 
        //- Collision stress derivative w.r.t. the volume fraction
        tmp<Field<scalar>> dTaudTheta
        (
            const Field<scalar>& alpha,
            const Field<scalar>& rho,
            const Field<scalar>& uRms
        ) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace ParticleStressModels
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //