pitchForkRing.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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    \\  /    A nd           | Copyright (C) 2011-2026 OpenFOAM Foundation
     \\/     M anipulation  |
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License
    This file is part of OpenFOAM.
 
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    under the terms of the GNU General Public License as published by
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#include "pitchForkRing.H"
#include "addToRunTimeSelectionTable.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace tetherPotentials
{
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
defineTypeNameAndDebug(pitchForkRing, 0);
 
addToRunTimeSelectionTable
(
    tetherPotential,
    pitchForkRing,
    dictionary
);
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
pitchForkRing::pitchForkRing
(
    const word& name,
    const dictionary& tetherPotentialProperties
)
:
    tetherPotential(name, tetherPotentialProperties),
    pitchForkRingCoeffs_
    (
        tetherPotentialProperties.typeDict(typeName)
    ),
    mu_(pitchForkRingCoeffs_.template lookup<scalar>("mu")),
    alpha_(pitchForkRingCoeffs_.template lookup<scalar>("alpha")),
    rOrbit_(pitchForkRingCoeffs_.template lookup<scalar>("rOrbit"))
{}
 
 
// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
scalar pitchForkRing::energy(const vector r) const
{
    scalar p = sqrt(r.x()*r.x() + r.y()*r.y());
 
    scalar pMinusRSqr = sqr(p - rOrbit_);
 
    return
       -0.5 * mu_ * pMinusRSqr
      + 0.25 * pMinusRSqr * pMinusRSqr
      + 0.5 * alpha_ * r.z() * r.z();
}
 
 
vector pitchForkRing::force(const vector r) const
{
    scalar p = sqrt(r.x()*r.x() + r.y()*r.y());
 
    scalar pMinusR = (p - rOrbit_);
 
    return vector
    (
        (mu_ - sqr(pMinusR)) * pMinusR * r.x()/(p + vSmall),
        (mu_ - sqr(pMinusR)) * pMinusR * r.y()/(p + vSmall),
      - alpha_ * r.z()
    );
}
 
 
bool pitchForkRing::read(const dictionary& tetherPotentialProperties)
{
    tetherPotential::read(tetherPotentialProperties);
 
    pitchForkRingCoeffs_ =
        tetherPotentialProperties.typeDict(typeName);
 
    pitchForkRingCoeffs_.lookup("mu") >> mu_;
    pitchForkRingCoeffs_.lookup("alpha") >> alpha_;
    pitchForkRingCoeffs_.lookup("rOrbit") >> rOrbit_;
 
    return true;
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace tetherPotentials
} // End namespace Foam
 
// ************************************************************************* //