src/lagrangian/molecularDynamics/potential/tetherPotential/derived/pitchForkRing/pitchForkRing.C

   1 /*---------------------------------------------------------------------------*\
   2   =========                 |
   3   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   4    \\    /   O peration     |
   5     \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
   6      \\/     M anipulation  |
   7 -------------------------------------------------------------------------------
   8 License
   9     This file is part of OpenFOAM.
  10
  11     OpenFOAM is free software: you can redistribute it and/or modify it
  12     under the terms of the GNU General Public License as published by
  13     the Free Software Foundation, either version 3 of the License, or
  14     (at your option) any later version.
  15
  16     OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
  17     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19     for more details.
  20
  21     You should have received a copy of the GNU General Public License
  22     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 \*---------------------------------------------------------------------------*/
  25
  26 #include "pitchForkRing.H"
  27 #include "addToRunTimeSelectionTable.H"
  28
  29 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
  30
  31 namespace Foam
  32 {
  33 namespace tetherPotentials
  34 {
  35
  36 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
  37
  38 defineTypeNameAndDebug(pitchForkRing, 0);
  39
  40 addToRunTimeSelectionTable
  41 (
  42     tetherPotential,
  43     pitchForkRing,
  44     dictionary
  45 );
  46
  47
  48 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
  49
  50 pitchForkRing::pitchForkRing
  51 (
  52     const word& name,
  53     const dictionary& tetherPotentialProperties
  54 )
  55 :
  56     tetherPotential(name, tetherPotentialProperties),
  57     pitchForkRingCoeffs_
  58     (
  59         tetherPotentialProperties.subDict(typeName + "Coeffs")
  60     ),
  61     mu_(readScalar(pitchForkRingCoeffs_.lookup("mu"))),
  62     alpha_(readScalar(pitchForkRingCoeffs_.lookup("alpha"))),
  63     rOrbit_(readScalar(pitchForkRingCoeffs_.lookup("rOrbit")))
  64 {}
  65
  66
  67 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
  68
  69 scalar pitchForkRing::energy(const vector r) const
  70 {
  71     scalar p = sqrt(r.x()*r.x() + r.y()*r.y());
  72
  73     scalar pMinusRSqr = sqr(p - rOrbit_);
  74
  75     return
  76        -0.5 * mu_ * pMinusRSqr
  77       + 0.25 * pMinusRSqr * pMinusRSqr
  78       + 0.5 * alpha_ * r.z() * r.z();
  79 }
  80
  81
  82 vector pitchForkRing::force(const vector r) const
  83 {
  84     scalar p = sqrt(r.x()*r.x() + r.y()*r.y());
  85
  86     scalar pMinusR = (p - rOrbit_);
  87
  88     return vector
  89     (
  90         (mu_ - sqr(pMinusR)) * pMinusR * r.x()/(p + VSMALL),
  91         (mu_ - sqr(pMinusR)) * pMinusR * r.y()/(p + VSMALL),
  92       - alpha_ * r.z()
  93     );
  94 }
  95
  96
  97 bool pitchForkRing::read(const dictionary& tetherPotentialProperties)
  98 {
  99     tetherPotential::read(tetherPotentialProperties);
 100
 101     pitchForkRingCoeffs_ =
 102         tetherPotentialProperties.subDict(typeName + "Coeffs");
 103
 104     pitchForkRingCoeffs_.lookup("mu") >> mu_;
 105     pitchForkRingCoeffs_.lookup("alpha") >> alpha_;
 106     pitchForkRingCoeffs_.lookup("rOrbit") >> rOrbit_;
 107
 108     return true;
 109 }
 110
 111
 112 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 113
 114 } // End namespace tetherPotentials
 115 } // End namespace Foam
 116
 117 // ************************************************************************* //