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Printing out mixture-averaged diffusion coefficients in Openfoam

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Old   July 16, 2023, 11:43
Default Printing out mixture-averaged diffusion coefficients in Openfoam
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Harish Gopal
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Hi everyone,


I hope you are having a nice day !



For my research, I am studying the dynamics of premixed flames forced by harmonic velocity disturbances. To achieve this goal, I am running some forced computations of a slot-stabilized flame in OpenFoam (reactingFoam).


I am using mixture averaged Wilke Rule to compute the species diffusion coefficients (mixture averaged Dmix) from the binary diffusion coefficients (Dij). These binary diffusion coefficients, I am specifying as a table in my thermophysicalTransport file (Specify transport properties using function2 object in OpenFoam).


To check if the mixture-averaged diffusion coefficient is calculated correctly (and to check if openfoam has correctly read the table values that I gave in), I want to print the mixture averaged diffusion coefficients (Dmix). The definition of Dmix is given in the file /opt/openfoam10/src/ThermophysicalTransportModels/laminar/Fickian/Fickian.H as the following


//- Effective mass diffusion coefficient
// for a given specie mass-fraction [kg/m/s]
virtual tmp<volScalarField> DEff(const volScalarField& Yi) const;


Please, can someone tell me how to print it each and every write time interval along with p,T, U and so on..


I know it is possible to print out the thermophysical properties by writing print statements in the solver file. For example, suppose one wants to print kappa (thermal conductivity), one has to add the following lines to the reactingFoam.c file

k_output = thermo.kappa();


and then add the following in the createFields.H file


volScalarField k_output
(
IOobject
(
"k_output",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::AUTO_WRITE
),
thermo.kappa()
);


But how do I do the same for DEff ? The reason I ask this is, DEff is a quantity which varies for each species, no ? So should I write it species-by-species


for example: thermophysicalTransport.DEff('O2'), thermophysicalTransport.DEff('CH4')... and so on..


I would be extremely grateful if one of you can give some insight on this please.


Thanks,


Harish
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Old   February 16, 2024, 22:54
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Hi Harish,

I was just wondering if you have got the answer to your question or somehow figured it out yourself. This is a question for me too. I would appreciate it if you verified whether or not your method works as expected.
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