PairSpringSliderDashpot.H

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
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-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::PairSpringSliderDashpot
 
Description
    Pair forces between particles colliding with a spring, slider, damper model
 
\*---------------------------------------------------------------------------*/
 
#ifndef PairSpringSliderDashpot_H
#define PairSpringSliderDashpot_H
 
#include "PairModel.H"
#include "CollisionRecordList.H"
#include "mathematicalConstants.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
/*---------------------------------------------------------------------------*\
                   Class PairSpringSliderDashpot Declaration
\*---------------------------------------------------------------------------*/
 
template<class CloudType>
class PairSpringSliderDashpot
:
    public PairModel<CloudType>
{
    // Private data
 
        //- Effective Young's modulus value, assuming both particles have
        //  the same E value
        scalar Estar_;
 
        //- Effective shear modulus value, assuming both particles have
        //  the same Poisson's ratio and Young's modulus
        scalar Gstar_;
 
        //- alpha-coefficient, related to coefficient of restitution
        scalar alpha_;
 
        //- Spring power (b = 1 for linear, b = 3/2 for Hertzian)
        scalar b_;
 
        //- Coefficient of friction in for tangential sliding
        scalar mu_;
 
        //- Cohesion energy density [J/m^3]
        scalar cohesionEnergyDensity_;
 
        //- Switch cohesion on and off
        bool cohesion_;
 
        //- The number of steps over which to resolve the minimum
        //  harmonic approximation of the collision period
        scalar collisionResolutionSteps_;
 
        //- Volume factor for determining the equivalent size of a
        //  parcel where nParticles is not 1.  The equivalent size of
        //  the parcel is
        //      parcelEquivVolume = volumeFactor*nParticles*p.volume()
        //  so
        //      parcelEquivD = cbrt(volumeFactor*nParticles)*p.d()
        //  + When volumeFactor = 1, the particles are compressed
        //    together so that the equivalent volume of the parcel is
        //    the sum of the constituent particles
        //  + When volumeFactor = 3*sqrt(2)/pi, the particles are
        //    close packed, but uncompressed.
        //  + When volumeFactor > 3*sqrt(2)/pi, the particles loosely
        //    grouped.
        // 3*sqrt(2)/pi = 1.350474 is the volume factor for close
        // packing, i.e pi/(3*sqrt(2)) is the maximum close packing
        // factor
        scalar volumeFactor_;
 
        //- Switch to control use of equivalent size particles.  Used
        //  because the calculation can be very expensive.
        bool useEquivalentSize_;
 
 
    // Private Member Functions
 
        //- Find the appropriate properties for determining the minimum
        //  allowable timestep
        void findMinMaxProperties
        (
            scalar& RMin,
            scalar& rhoMax,
            scalar& vMagMax
        ) const;
 
public:
 
    //- Runtime type information
    TypeName("pairSpringSliderDashpot");
 
 
    // Constructors
 
        //- Construct from dictionary
        PairSpringSliderDashpot(const dictionary& dict, CloudType& cloud);
 
 
    //- Destructor
    virtual ~PairSpringSliderDashpot();
 
 
    // Member Functions
 
        //- Return the volumeFactor
        inline scalar volumeFactor() const
        {
            return volumeFactor_;
        }
 
        //- Return the area of overlap between two spheres of radii rA and rB,
        //  centres separated by a distance rAB.  Assumes rAB < (rA + rB).
        inline scalar overlapArea(scalar rA, scalar rB, scalar rAB) const
        {
            // From:
            // http://mathworld.wolfram.com/Sphere-SphereIntersection.html
            return
                mathematical::pi/4.0
               /sqr(rAB)
               *(
                    (-rAB + rA - rB)
                   *(-rAB - rA + rB)
                   *(-rAB + rA + rB)
                   *( rAB + rA + rB)
                );
        }
 
        //- Whether the PairModel has a timestep limit that will
        //  require subCycling
        virtual bool controlsTimestep() const;
 
        //- For PairModels that control the timestep, calculate the
        //  number of subCycles needed to satisfy the minimum
        //  allowable timestep
        virtual label nSubCycles() const;
 
        //- Calculate the pair interaction between parcels
        virtual void evaluatePair
        (
            typename CloudType::parcelType& pA,
            typename CloudType::parcelType& pB
        ) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#ifdef NoRepository
#   include "PairSpringSliderDashpot.C"
#endif
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //