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

   1 /*---------------------------------------------------------------------------*\
   2   =========                 |
   3   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   4    \\    /   O peration     |
   5     \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
   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 the
  13     Free Software Foundation; either version 2 of the License, or (at your
  14     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, write to the Free Software Foundation,
  23     Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  24
  25 \*---------------------------------------------------------------------------*/
  26
  27 #include "restrainedHarmonicSpring.H"
  28 #include "addToRunTimeSelectionTable.H"
  29
  30 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
  31
  32 namespace Foam
  33 {
  34 namespace tetherPotentials
  35 {
  36
  37 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
  38
  39 defineTypeNameAndDebug(restrainedHarmonicSpring, 0);
  40
  41 addToRunTimeSelectionTable
  42 (
  43     tetherPotential,
  44     restrainedHarmonicSpring,
  45     dictionary
  46 );
  47
  48
  49 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
  50
  51 restrainedHarmonicSpring::restrainedHarmonicSpring
  52 (
  53     const word& name,
  54     const dictionary& tetherPotentialProperties
  55 )
  56 :
  57     tetherPotential(name, tetherPotentialProperties),
  58     restrainedHarmonicSpringCoeffs_
  59     (
  60         tetherPotentialProperties.subDict(typeName + "Coeffs")
  61     ),
  62     springConstant_
  63     (
  64         readScalar(restrainedHarmonicSpringCoeffs_.lookup("springConstant"))
  65     ),
  66     rR_
  67     (
  68         readScalar(restrainedHarmonicSpringCoeffs_.lookup("rR"))
  69     )
  70 {}
  71
  72 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
  73
  74 scalar restrainedHarmonicSpring::energy(const vector r) const
  75 {
  76     scalar magR = mag(r);
  77
  78     if (magR < rR_)
  79     {
  80         return 0.5 * springConstant_ * magSqr(r);
  81     }
  82     else
  83     {
  84         return 0.5 * springConstant_ * rR_ * rR_
  85           + springConstant_ * rR_ * (magR - rR_);
  86     }
  87 }
  88
  89
  90 vector restrainedHarmonicSpring::force(const vector r) const
  91 {
  92     scalar magR = mag(r);
  93
  94     if (magR < rR_)
  95     {
  96         return -springConstant_ * r;
  97     }
  98     else
  99     {
 100         return -springConstant_ * rR_ * r / magR;
 101     }
 102 }
 103
 104
 105 bool restrainedHarmonicSpring::read
 106 (
 107     const dictionary& tetherPotentialProperties
 108 )
 109 {
 110     tetherPotential::read(tetherPotentialProperties);
 111
 112     restrainedHarmonicSpringCoeffs_ =
 113         tetherPotentialProperties.subDict(typeName + "Coeffs");
 114
 115     restrainedHarmonicSpringCoeffs_.lookup("springConstant") >> springConstant_;
 116     restrainedHarmonicSpringCoeffs_.lookup("rR") >> rR_;
 117
 118     return true;
 119 }
 120
 121
 122 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 123
 124 } // End namespace tetherPotentials
 125 } // End namespace Foam
 126
 127 // ************************************************************************* //