Difference between revisions of "FireFoam"

Revision as of 15:39, 6 April 2019

fireFoam

   Transient solver for fires and turbulent diffusion flames with reacting
   particle clouds, surface film and pyrolysis modelling.

1 Solution Strategy

The source code can be found in fireFoam.C

 
 
/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Application
    fireFoam
 
Group
    grpCombustionSolvers
 
Description
    Transient solver for fires and turbulent diffusion flames with reacting
    particle clouds, surface film and pyrolysis modelling.
 
\*---------------------------------------------------------------------------*/
 
#include "fvCFD.H"
#include "turbulentFluidThermoModel.H"
#include "basicReactingCloud.H"
#include "surfaceFilmModel.H"
#include "pyrolysisModelCollection.H"
#include "radiationModel.H"
#include "SLGThermo.H"
#include "solidChemistryModel.H"
#include "psiReactionThermo.H"
#include "CombustionModel.H"
#include "pimpleControl.H"
#include "fvOptions.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
int main(int argc, char *argv[])
{
    argList::addNote
    (
        "Transient solver for fires and turbulent diffusion flames"
        " with reacting particle clouds, surface film and pyrolysis modelling."
    );
 
    #include "postProcess.H"
 
    #include "addCheckCaseOptions.H"
    #include "setRootCaseLists.H"
    #include "createTime.H"
    #include "createMesh.H"
    #include "createControl.H"
    #include "createFields.H"
    #include "createFieldRefs.H"
    #include "initContinuityErrs.H"
    #include "createTimeControls.H"
    #include "compressibleCourantNo.H"
    #include "setInitialDeltaT.H"
    #include "createRegionControls.H"
 
    turbulence->validate();
 
    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
    Info<< "\nStarting time loop\n" << endl;
 
    while (runTime.run())
    {
        #include "readTimeControls.H"
        #include "compressibleCourantNo.H"
        #include "solidRegionDiffusionNo.H"
        #include "setMultiRegionDeltaT.H"
        #include "setDeltaT.H"
 
        ++runTime;
 
        Info<< "Time = " << runTime.timeName() << nl << endl;
 
        parcels.evolve();
 
        surfaceFilm.evolve();
 
        if(solvePyrolysisRegion)
        {
            pyrolysis.evolve();
        }
 
        if (solvePrimaryRegion)
        {
            #include "rhoEqn.H"
 
            // --- PIMPLE loop
            while (pimple.loop())
            {
                #include "UEqn.H"
                #include "YEEqn.H"
 
                // --- Pressure corrector loop
                while (pimple.correct())
                {
                    #include "pEqn.H"
                }
 
                if (pimple.turbCorr())
                {
                    turbulence->correct();
                }
            }
 
            rho = thermo.rho();
        }
 
        runTime.write();
 
        runTime.printExecutionTime(Info);
    }
 
    Info<< "End" << endl;
 
    return 0;
}
 
 
// ************************************************************************* //
 

2 Equations

2.1 Equations Liquid Film

The equation describing the evolution of the liquid film can be found in http://www.ilasseurope.org/ICLASS/iclass2012_Heidelberg/Contributions/Paper-pdfs/Contribution1294_b.pdf and https://www.witpress.com/Secure/elibrary/papers/MPF11/MPF11020FU1.pdf. A description of the method used to derive the equation can be found in https://www.researchgate.net/profile/Petr_Vita/publication/313655371_Thin_Film_Fluid_Flow_Simulation_on_Rotating_Discs/links/58a1a592a6fdccf5e9707665/Thin-Film-Fluid-Flow-Simulation-on-Rotating-Discs.pdf.

The conservation of mass reads:

(x)

represents the mean film velocity, the film height and mass source term resulting from the impingement of the liquid droplets on the film surface. The momentum conservation reads:

(x)

represents the pressure and represents the contribution to the momentum by the impinging droplets.

The energy equation reads:

(x)

represents the mean film enthalpy and represents the contribution of the impinging droplets to the energy equation.

2.2 Equations Fluid

2.2.1 Momentum conservation

The equation of motion are written for a moving frame of reference. They are however formulated for the absolute velocity (the derivation of the equations of motion can be found in https://openfoamwiki.net/index.php/See_the_MRF_development and also in https://diglib.tugraz.at/download.php?id=581303c7c91f9&location=browse. Some additional information can be found in https://pingpong.chalmers.se/public/pp/public_courses/course07056/published/1497955220499/resourceId/3711490/content/UploadedResources/HakanNilssonRotatingMachineryTrainingOFW11-1.pdf):

(2)

represent the velocity, the relative veloicty, the gravitational acceleration, the pressure minus the hydrostatic pressure and and are the viscose and turbulent stresses. Note that since the relative velocity appears in the divergence term, the face flux appearing in the finite volume discretization of the momentum equation should be calculated with the relative velocity. represents the force excreted by the particles on the fluid.

The source code can be found in Ueqn.H:

 
 
      MRF.correctBoundaryVelocity(U);
 
    fvVectorMatrix UEqn
    (
        fvm::ddt(rho, U) + fvm::div(phi, U)
      + MRF.DDt(rho, U)
      + turbulence->divDevRhoReff(U)
     ==
        parcels.SU(U)
      + fvOptions(rho, U)
    );
 
    UEqn.relax();
 
    fvOptions.constrain(UEqn);
 
    if (pimple.momentumPredictor())
    {
        solve
        (
            UEqn
          ==
            fvc::reconstruct
            (
                (
                  - ghf*fvc::snGrad(rho)
                  - fvc::snGrad(p_rgh)
                )*mesh.magSf()
            )
        );
 
        fvOptions.correct(U);
        K = 0.5*magSqr(U);
    }