restrainedHarmonicSpring.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
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    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
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    for more details.
 
    You should have received a copy of the GNU General Public License
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#include "restrainedHarmonicSpring.H"
#include "addToRunTimeSelectionTable.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace tetherPotentials
{
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
defineTypeNameAndDebug(restrainedHarmonicSpring, 0);
 
addToRunTimeSelectionTable
(
    tetherPotential,
    restrainedHarmonicSpring,
    dictionary
);
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
restrainedHarmonicSpring::restrainedHarmonicSpring
(
    const word& name,
    const dictionary& tetherPotentialProperties
)
:
    tetherPotential(name, tetherPotentialProperties),
    restrainedHarmonicSpringCoeffs_
    (
        tetherPotentialProperties.subDict(typeName + "Coeffs")
    ),
    springConstant_
    (
        readScalar(restrainedHarmonicSpringCoeffs_.lookup("springConstant"))
    ),
    rR_
    (
        readScalar(restrainedHarmonicSpringCoeffs_.lookup("rR"))
    )
{}
 
// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
scalar restrainedHarmonicSpring::energy(const vector r) const
{
    scalar magR = mag(r);
 
    if (magR < rR_)
    {
        return 0.5 * springConstant_ * magSqr(r);
    }
    else
    {
        return 0.5 * springConstant_ * rR_ * rR_
          + springConstant_ * rR_ * (magR - rR_);
    }
}
 
 
vector restrainedHarmonicSpring::force(const vector r) const
{
    scalar magR = mag(r);
 
    if (magR < rR_)
    {
        return -springConstant_ * r;
    }
    else
    {
        return -springConstant_ * rR_ * r / magR;
    }
}
 
 
bool restrainedHarmonicSpring::read
(
    const dictionary& tetherPotentialProperties
)
{
    tetherPotential::read(tetherPotentialProperties);
 
    restrainedHarmonicSpringCoeffs_ =
        tetherPotentialProperties.subDict(typeName + "Coeffs");
 
    restrainedHarmonicSpringCoeffs_.lookup("springConstant") >> springConstant_;
    restrainedHarmonicSpringCoeffs_.lookup("rR") >> rR_;
 
    return true;
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace tetherPotentials
} // End namespace Foam
 
// ************************************************************************* //