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-   -   OpenFoam using chemkin to make new species (http://www.cfd-online.com/Forums/openfoam-solving/86947-openfoam-using-chemkin-make-new-species.html)

D.R. April 6, 2011 18:49

OpenFoam using chemkin to make new species
 
Hello,
I am using the chemkin solver to do a reaction for urea in my chem.inp file
//
ELEMENTS
C H O N
END
SPECIES
CH4N20 HNCO NH3 N2 O2 H2O NO
END
REACTIONS
CH4N2O => NH3 + HNCO 2.62E4 1.0 1.61E4
END
//
This seems like the correct solver, however, the molar fraction of urea stays constant and the NH3 and HNCO fractions do not increase, they stay at 0. Is there something wrong with this setup?

kalle April 7, 2011 01:53

Post your case (or as much of it as you are allowed to) and the output from the solver... then we have a possibility to see what's up!

D.R. April 7, 2011 11:55

The reactions seem to not be taking place even though they should be.

here is the out.log file

Time = 0.24316

Evolving Spray
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.000111363, Final residual = 7.84706e-07, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 0.000130545, Final residual = 5.54606e-07, No Iterations 2
DILUPBiCG: Solving for Uz, Initial residual = 1.04772e-05, Final residual = 2.36695e-07, No Iterations 1
DILUPBiCG: Solving for CH4N2O, Initial residual = 0.000232098, Final residual = 7.27763e-07, No Iterations 2
DILUPBiCG: Solving for HNCO, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for NH3, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for O2, Initial residual = 9.70172e-05, Final residual = 5.69026e-07, No Iterations 2
DILUPBiCG: Solving for H2O, Initial residual = 7.13753e-05, Final residual = 3.23582e-07, No Iterations 2
DILUPBiCG: Solving for NO, Initial residual = 9.70173e-05, Final residual = 5.69026e-07, No Iterations 2
DILUPBiCG: Solving for h, Initial residual = 7.97133e-05, Final residual = 3.31688e-07, No Iterations 2
DICPCG: Solving for p, Initial residual = 0.0116091, Final residual = 7.76861e-10, No Iterations 99
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 2.56051e-13, global = 6.9169e-16, cumulative = -1.16239e-11
DICPCG: Solving for p, Initial residual = 0.00172367, Final residual = 8.31493e-10, No Iterations 91
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 2.53289e-13, global = -2.82293e-15, cumulative = -1.16267e-11
DILUPBiCG: Solving for epsilon, Initial residual = 1.11152e-05, Final residual = 4.46099e-07, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 1.33413e-05, Final residual = 3.01646e-07, No Iterations 1

Number of parcels in system.... | 322904
Injected liquid mass........... | 79.5796 mg
Liquid Mass in system.......... | 5.07001 mg
SMD, Dmax...................... | 35.3345 mu, 97.3992 mu
Added gas mass................. | 31.9709 mg
Evaporation Continuity Error... | -42.5387 mg
max T = max(T) [0 0 0 1 0 0 0] 1150 K
min T = min(T) [0 0 0 1 0 0 0] 824.49 K
ExecutionTime = 144825 s ClockTime = 145381 s

Courant Number mean: 0.0248724 max: 0.2412
Calculating averages


here is the chemistry properties in the constant folder
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.6 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format binary;
class dictionary;
location "constant";
object chemistryProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


psiChemistryModel ODEChemistryModel<gasThermoPhysics>;

chemistry on;

chemistrySolver ode;

initialChemicalTimeStep 1e-08;

sequentialCoeffs
{
cTauChem 0.001;
}

EulerImplicitCoeffs
{
cTauChem 0.05;
equilibriumRateLimiter off;
}

odeCoeffs
{
ODESolver SIBS;
eps 0.05;
scale 1;
}


// ************************************************** *********************** //

D.R. April 7, 2011 16:27

figured out the problem, it was in the dieselFoam solver, i needed to comment out the turbulent time constant, because it caused instabilities in the chemistry solver, and was not necessary to the solution.


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