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 sto16 January 12, 2012 10:37

calculation of thermal conductivity in reactingFoam

hello,

i am comparing simulation results in fluent to simulation results in openfoam.
in my case i am working with two species which stream over a heated wall in reactingFoam. (in OF 2.0.1)
now i want to set all bc's and coefficients for calculations to the same value.

in fluent the calculations of cp, mu and kappa are done using a polynomial.
i managed to fit the values for cp and mu in reactingFoam. this was simply done in my thermo.compressibleGas-file by changing the coeffs and the transport-values As and Ts. but i can not find the place where i can see and change the calculation of the thermal conductivity kappa(?) in reactingFoam.

could anybody help me and explain how and where thermal conductivity is calculated?

thank you....

tomek

 sto16 January 16, 2012 10:37

Hey,

Now I am working with OpenFoam for almost two months and I think after some time of searching for the calculations used by reactingFoam I understood how it is managed with its subdirectories.

Please correct me in my thoughts if i am wrong:
When i have choosen hsPsiMixtureThermo<reactingMixture<sutherlandTrans port<specieThermo<janafThermo<perfectGas>>>>> I have to look for the calculations in this Files?

So conductivity kappa is calculated in sutherlandTransport by using mu, R and Cv.
Also the viscosity mu and the thermal diffusivity alpha is calculated here.
The turbulent parts alphat and mut are calculated according to the turbulenceModel which is choosen (here: kOmegaSSt) and calculated in the belonging directory.

In the end it is added to alphaEff and muEff.

Is this right?

Now I went on searching for the mass diffusivity but I could not find any calculation handling this problem.
In fluent, diffusivity is calculated using Fick with Chapman-Enskog and Lennard-Jones parameters.
Is there something comparable in OpenFoam?

The only thing I found was the effective Diffusivity, but this is used for the k and omega terms in the turbulence-calculation....

So please help me if you know how and where mass diffusivity is calculated, or what i have to change in my settings to achieve that.

thanks...

tomek

 kmpang April 20, 2012 08:15

Hi Tomek,

Do you have any update with the calculation including mass diffusivity? I'm looking into it too but to do this, it seems like we need to modify the code. :o

Pang.

 sto16 April 24, 2012 08:02

hey pang,

there are no separate calculations for mass diffusivity and thermal diffusivity.

so if u need them u'll have to construct a new solver which includes the terms....

tomek

 kmpang April 26, 2012 02:32

Morning Tomek,

Yes, I realised that too. There are some 'addi-on' codes which can be integrated into reactingFoam but most of them seem to work for the older-version-OpenFOAM. I'm using 2.0.x and hence thinking how to do it. :rolleyes:

Thanks.

Best regards,
Pang.

 carl_xw4 May 9, 2012 15:22

Hi all,

In laminar combustion cases, in order to calculate viscosity (mu) and thermal conductivity (alpha), we define As and Ts in the OpenFOAM thermodynamic properties format (as given in the reactingFoam tutorial). As such, mu is calculated by Sutherland Transport equation while alpha should be calculated using Eucken model based on mu. Kindly correct me if I am wrong.

However, I still have a question regarding this mu and alpha calculation. If we provide the chemistry and thermo data in the directory \$FOAM_RUN/chemkin, thermo data is in the form of

O2 121386O 2 G 200.00 5000.00 1000.000

and seven coefficients for Janaff interpolation are given for first and second temperature ranges, respectively. This is in the form of typical Chemkin format (as given in the dieselFoam tutorial). In this case, how are both mu and alpha calculated?

Regards,
Carl.

 carl_xw4 May 15, 2012 05:18

2 Attachment(s)

Carl

 kmpang July 27, 2012 03:35

Hello,

In case anyone of you is still interested to know: The As and Ts values are fixed at 1.67212e-06 and 170.672, respectively.

Check chemkinLexer.L

Best regards,
Pang

 hg2lf February 19, 2013 08:29

So what do you want to say? Don't you know why the values are the same?

 yash.aesi September 11, 2013 15:23

regarding reactingFoam solver

greetings oll ,

i am using OF 2.2 and trying to solve my case with the reacting Foam solver
the doubt in my mind is that do i need to use chemkin folder along with 0, constant and system in OF 2.2 as it already have a reaction and thermo. file in constant folder as given in counterflowflame2D.