Implementing NASA 9 Polynomials in janaf thermo model

hn00 · March 19, 2023, 08:42

I am using OpenFOAM-v1706 and I wanna implement NASA 9 polynomials into the janaf thermo model, which currently takes only NASA 7. Is there an easy way to do that by editing and compiling src files?

Also, if there isn't, how to give Cp as a function of temperature?

Thank you.

Tobermory · March 20, 2023, 11:50

Sounds like you need to implement your own version of the Janaf class, updating the member functions to use 9 coeffs instead of 7. You can then compile this as your own user library. Shouldn't be too tricky.

überschwupper · March 28, 2023, 02:38

I agree with Tobermory. Adding to this, do this in your personal environment ($FOAM_USER_LIBBIN) otherwise you will compromise your OpenFoam installation. Copy the janaf Folder to your own OF directory, rename it to janaf9 or whatever and modify the file with the inline functions (i think it was janafI.H) to match with the JANAF 9 polynomials. Keep in mind that you have to update Cp, Enthalpy and Entropy and reference in there.

March 19, 2023, 08:42	Implementing NASA 9 Polynomials in janaf thermo model	#1
hn00 New Member Nathuram Godse Join Date: Mar 2023 Posts: 1 Rep Power: 0	I am using OpenFOAM-v1706 and I wanna implement NASA 9 polynomials into the janaf thermo model, which currently takes only NASA 7. Is there an easy way to do that by editing and compiling src files? Also, if there isn't, how to give Cp as a function of temperature? Thank you.

March 28, 2023, 02:38		#3
überschwupper Member Join Date: Jan 2022 Location: Germany Posts: 72 Rep Power: 4	I agree with Tobermory. Adding to this, do this in your personal environment ($FOAM_USER_LIBBIN) otherwise you will compromise your OpenFoam installation. Copy the janaf Folder to your own OF directory, rename it to janaf9 or whatever and modify the file with the inline functions (i think it was janafI.H) to match with the JANAF 9 polynomials. Keep in mind that you have to update Cp, Enthalpy and Entropy and reference in there. Tobermory likes this.

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March 20, 2023, 11:50		#2
Tobermory Senior Member Join Date: Apr 2020 Location: UK Posts: 668 Rep Power: 14	Sounds like you need to implement your own version of the Janaf class, updating the member functions to use 9 coeffs instead of 7. You can then compile this as your own user library. Shouldn't be too tricky.