[Amirreza_pro]

Hey guys
I hope that you are doing well.

I have a problem with ''Janaf thermo error''.

I'm using reactingFoam in openFoam and get Janaf thermo error.
My case is that, I changed the mechanism in openaFoam and used my mechanism with 41 species, I could convert my chemkin files with the help of chemkintoFoam command succesfully.
But when I run the simulation I get also same error:
attempt to use janafThermo<equationOfState> out of temperature range 300 -> 3000;

Is there a way to resolve this problem ?

All the best
Amirreza

[NLeb]

Sounds like you're using JANAF coefficients in your thermophysicalProperties file, and at some point in your simulation, the temperature goes below 300K or above 3000K. These limits are specified by the user with Tlow and Thigh in the relevant thermo dictionary.

Here's an example of O2's JANAF entry from $FOAM_TUTORIALS/combustion/reactingFoam/laminar/counterFlowFlame2D/ where the JANAF coefficients are found in constant/thermo.compressibleGas (it might be a different file for you)

thermodynamics
    {
        Tlow            200;
        Thigh           5000;
        Tcommon         1000;
        highCpCoeffs    ( 3.69758 0.00061352 -1.25884e-07 1.77528e-11 -1.13644e-15 -1233.93 3.18917 );
        lowCpCoeffs     ( 3.21294 0.00112749 -5.75615e-07 1.31388e-09 -8.76855e-13 -1005.25 6.03474 );
    }

Here, Tlow is 200 and Thigh is 5000 - these are the lower and upper bounds for validity of the polynomial coefficients specified in highCpCoeffs and lowCpCoeffs. OpenFOAM halts execution and throws an error if it ever sees a temperature outside of this range.

So you have a few options:

• Find a different set of JANAF coefficients which are valid for the temperature range you need
• Use a different thermo method instead of JANAF
• Adjust your simulation such that the temperature never goes outside the current Tlow and Thigh you have

More information about JANAF here: https://openfoamwiki.net/index.php/Contrib/Janaf

If you want to see exactly what the JANAF code is doing (in v2012), see this: https://www.openfoam.com/documentati...hermoI_8H.html

Hope this helps!

[Amirreza_pro]

Thanks foy your reply dear NLeb

[lliyuu]

I have been troubled by the same problem for several months, who can help me, thank you very much.

[Tobermory]

Nik summarises your options pretty clearly. My advice is to certainly employ #3, ie use the limitTemperature FO to keep the temperature within bounds during any initial transients. That certainly works well for me.

[lliyuu]

Thank you for your reply. In fact, I have used the limitTemperature method, but it has no effect. When the temperature reaches the upper or lower limit of the temperature I set, the simulation will stop.