VariableHardSphere.C

Go to the documentation of this file.

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2015 OpenFOAM Foundation
-------------------------------------------------------------------------------
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/>.
 
\*---------------------------------------------------------------------------*/
 
#include "VariableHardSphere.H"
#include "constants.H"
 
using namespace Foam::constant::mathematical;
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
template<class CloudType>
Foam::VariableHardSphere<CloudType>::VariableHardSphere
(
    const dictionary& dict,
    CloudType& cloud
)
:
    BinaryCollisionModel<CloudType>(dict, cloud, typeName),
    Tref_(this->coeffDict().getScalar("Tref"))
{}
 
 
// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
template<class CloudType>
Foam::VariableHardSphere<CloudType>::~VariableHardSphere()
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
template<class CloudType>
bool Foam::VariableHardSphere<CloudType>::active() const
{
    return true;
}
 
 
template<class CloudType>
Foam::scalar Foam::VariableHardSphere<CloudType>::sigmaTcR
(
    const typename CloudType::parcelType& pP,
    const typename CloudType::parcelType& pQ
) const
{
    const CloudType& cloud(this->owner());
 
    label typeIdP = pP.typeId();
    label typeIdQ = pQ.typeId();
 
    scalar dPQ =
        0.5
       *(
            cloud.constProps(typeIdP).d()
          + cloud.constProps(typeIdQ).d()
        );
 
    scalar omegaPQ =
        0.5
       *(
            cloud.constProps(typeIdP).omega()
          + cloud.constProps(typeIdQ).omega()
        );
 
    scalar cR = mag(pP.U() - pQ.U());
 
    if (cR < VSMALL)
    {
        return 0;
    }
 
    scalar mP = cloud.constProps(typeIdP).mass();
 
    scalar mQ = cloud.constProps(typeIdQ).mass();
 
    scalar mR = mP*mQ/(mP + mQ);
 
    // calculating cross section = pi*dPQ^2, where dPQ is from Bird, eq. 4.79
    scalar sigmaTPQ =
        pi*dPQ*dPQ
       *pow(2.0*physicoChemical::k.value()*Tref_/(mR*cR*cR), omegaPQ - 0.5)
       /exp(Foam::lgamma(2.5 - omegaPQ));
 
    return sigmaTPQ*cR;
}
 
 
template<class CloudType>
void Foam::VariableHardSphere<CloudType>::collide
(
    typename CloudType::parcelType& pP,
    typename CloudType::parcelType& pQ
)
{
    CloudType& cloud(this->owner());
 
    label typeIdP = pP.typeId();
    label typeIdQ = pQ.typeId();
    vector& UP = pP.U();
    vector& UQ = pQ.U();
 
    Random& rndGen = cloud.rndGen();
 
    scalar mP = cloud.constProps(typeIdP).mass();
 
    scalar mQ = cloud.constProps(typeIdQ).mass();
 
    vector Ucm = (mP*UP + mQ*UQ)/(mP + mQ);
 
    scalar cR = mag(UP - UQ);
 
    scalar cosTheta = 2.0*rndGen.sample01<scalar>() - 1.0;
 
    scalar sinTheta = sqrt(1.0 - cosTheta*cosTheta);
 
    scalar phi = twoPi*rndGen.sample01<scalar>();
 
    vector postCollisionRelU =
        cR
       *vector
        (
            cosTheta,
            sinTheta*cos(phi),
            sinTheta*sin(phi)
        );
 
    UP = Ucm + postCollisionRelU*mQ/(mP + mQ);
 
    UQ = Ucm - postCollisionRelU*mP/(mP + mQ);
}
 
 
// ************************************************************************* //