src/lagrangian/dieselSpray/spraySubModels/breakupModel/ETAB/ETAB.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 "ETAB.H"
  27 #include "addToRunTimeSelectionTable.H"
  28 #include "mathematicalConstants.H"
  29
  30 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
  31
  32 namespace Foam
  33 {
  34
  35     defineTypeNameAndDebug(ETAB, 0);
  36
  37     addToRunTimeSelectionTable
  38     (
  39         breakupModel,
  40         ETAB,
  41         dictionary
  42     );
  43 }
  44
  45
  46 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
  47
  48 Foam::ETAB::ETAB
  49 (
  50     const dictionary& dict,
  51     spray& sm
  52 )
  53 :
  54     breakupModel(dict, sm),
  55     coeffsDict_(dict.subDict(typeName + "Coeffs")),
  56     Cmu_(readScalar(coeffsDict_.lookup("Cmu"))),
  57     Comega_(readScalar(coeffsDict_.lookup("Comega"))),
  58     k1_(readScalar(coeffsDict_.lookup("k1"))),
  59     k2_(readScalar(coeffsDict_.lookup("k2"))),
  60     WeCrit_(readScalar(coeffsDict_.lookup("WeCrit"))),
  61     WeTransition_(readScalar(coeffsDict_.lookup("WeTransition"))),
  62     AWe_(0.0)
  63 {
  64     scalar k21 = k2_/k1_;
  65     AWe_ = (k21*sqrt(WeTransition_) - 1.0)/pow4(WeTransition_);
  66 }
  67
  68
  69 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
  70
  71 Foam::ETAB::~ETAB()
  72 {}
  73
  74
  75 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
  76
  77 void Foam::ETAB::breakupParcel
  78 (
  79     parcel& p,
  80     const scalar deltaT,
  81     const vector& Ug,
  82     const liquidMixtureProperties& fuels
  83 ) const
  84 {
  85     scalar T = p.T();
  86     scalar pc = spray_.p()[p.cell()];
  87     scalar r = 0.5*p.d();
  88     scalar r2 = r*r;
  89     scalar r3 = r*r2;
  90
  91     scalar rho = fuels.rho(pc, T, p.X());
  92     scalar sigma = fuels.sigma(pc, T, p.X());
  93     scalar mu = fuels.mu(pc, T, p.X());
  94
  95     // inverse of characteristic viscous damping time
  96     scalar rtd = 0.5*Cmu_*mu/(rho*r2);
  97
  98     // oscillation frequency (squared)
  99     scalar omega2 = Comega_*sigma/(rho*r3) - rtd*rtd;
 100
 101     if (omega2 > 0)
 102     {
 103         scalar omega = sqrt(omega2);
 104         scalar romega = 1.0/omega;
 105
 106         scalar rhog = spray_.rho()[p.cell()];
 107         scalar We = p.We(Ug, rhog, sigma);
 108         scalar Wetmp = We/WeCrit_;
 109
 110         scalar y1 = p.dev() - Wetmp;
 111         scalar y2 = p.ddev()*romega;
 112
 113         scalar a = sqrt(y1*y1 + y2*y2);
 114
 115         // scotty we may have break-up
 116         if (a + Wetmp > 1.0)
 117         {
 118             scalar phic = y1/a;
 119
 120             // constrain phic within -1 to 1
 121             phic = max(min(phic, 1), -1);
 122
 123             scalar phit = acos(phic);
 124             scalar phi = phit;
 125             scalar quad = -y2/a;
 126             if (quad < 0)
 127             {
 128                 phi = constant::mathematical::twoPi - phit;
 129             }
 130
 131             scalar tb = 0;
 132
 133             if (mag(p.dev()) < 1.0)
 134             {
 135                 scalar theta = acos((1.0 - Wetmp)/a);
 136
 137                 if (theta < phi)
 138                 {
 139                     if (constant::mathematical::twoPi - theta >= phi)
 140                     {
 141                         theta = -theta;
 142                     }
 143                     theta += constant::mathematical::twoPi;
 144                 }
 145                 tb = (theta-phi)*romega;
 146
 147                 // breakup occurs
 148                 if (deltaT > tb)
 149                 {
 150                     p.dev() = 1.0;
 151                     p.ddev() = -a*omega*sin(omega*tb + phi);
 152                 }
 153             }
 154
 155             // update droplet size
 156             if (deltaT > tb)
 157             {
 158                 scalar sqrtWe = AWe_*pow4(We) + 1.0;
 159                 scalar Kbr = k1_*omega*sqrtWe;
 160
 161                 if (We > WeTransition_)
 162                 {
 163                     sqrtWe = sqrt(We);
 164                     Kbr = k2_*omega*sqrtWe;
 165                 }
 166
 167                 scalar rWetmp = 1.0/Wetmp;
 168                 scalar cosdtbu = max(-1.0, min(1.0, 1.0 - rWetmp));
 169                 scalar dtbu = romega*acos(cosdtbu);
 170                 scalar decay = exp(-Kbr*dtbu);
 171
 172                 scalar rNew = decay*r;
 173                 if (rNew < r)
 174                 {
 175                     p.d() = 2*rNew;
 176                     p.dev() = 0;
 177                     p.ddev() = 0;
 178                 }
 179             }
 180         }
 181     }
 182     else
 183     {
 184         // reset droplet distortion parameters
 185         p.dev() = 0;
 186         p.ddev() = 0;
 187     }
 188 }
 189
 190
 191 // ************************************************************************* //