attempt to use janafThermo<equationOfState> out of temperature range 200 -> 5000;

Linse · October 12, 2016, 18:25

Dear Ahmed,

Did you think of the obvious - and probably cleanest - solution already? If you know the polynomials are sufficiently accurate for your simulations even below the limits, simply change the limits within the polynomial definition!

Within your "constant"-folder you should find the definitions of the gas properties for the simulation. Possibly they are within a file called "thermo.compressibleGas" or something similar. In a subsection of the file you will find parameters called "thermodynamics", where "Tlow" provides the lower limit for your Janaf-polynomials as read by reactingFoam.
Setting this limit to 280 should minimize the number of warnings in your case.

But be aware: This obviously will completely switch off any warning concerning temperature limits above that limit. If you want to be informed for temperatures between 280 and 300 K, you probably should find another solution...

Cheers,
Bernhard

sahmed · October 13, 2016, 12:22

Hello Bernhard
Thanks for your suggestion. In the recent chemical kinetic mechanism that I use, I have my Tlow as low as 200 for all the species. Even with that, I got janaf out of reach error msg. This has now been a global problem for all combustion solver users and there must be an inherent bug in the code. I think the developers should concentrate on it.
Please share if you have any other suggestion.
Thanks once again

~SFA

sheaker · October 13, 2016, 16:13

Hello. As I know there is a bug in openFoam 2.1.1 which leads to nonphysical results: Cooling during compression.
Here is example:
https://www.youtube.com/watch?v=KA--7CpiCTA

Unfortunately I can't find report of this bug.

It is fixed in openFoam 2.2.1.

sunjg13 · May 22, 2018, 09:22

Quote:

Originally Posted by sahmed

I solved the problem by decreasing the number of cores in my parallel runs. It is working fine now without showing any warning msg and taking unnecessary times.
Hope this will help others.

Yes, it really helps a lot!!!
The last piece of this thread is the most useful one, I think

Of course, I hope we can find some other ways to get rid of this problem.

IFX21 · March 23, 2022, 17:47

I solved this problem by reducing the timestep "deltaT" in "controlDict" files. The error disappears but still need some investigation on what really goes behind it

lliyuu · February 26, 2023, 21:06

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

October 12, 2016, 18:25	Setting JANAF-limits	#21
Linse Senior Member Bernhard Linseisen Join Date: May 2010 Location: Heilbronn Posts: 183 Blog Entries: 1 Rep Power: 15	Dear Ahmed, Did you think of the obvious - and probably cleanest - solution already? If you know the polynomials are sufficiently accurate for your simulations even below the limits, simply change the limits within the polynomial definition! Within your "constant"-folder you should find the definitions of the gas properties for the simulation. Possibly they are within a file called "thermo.compressibleGas" or something similar. In a subsection of the file you will find parameters called "thermodynamics", where "Tlow" provides the lower limit for your Janaf-polynomials as read by reactingFoam. Setting this limit to 280 should minimize the number of warnings in your case. But be aware: This obviously will completely switch off any warning concerning temperature limits above that limit. If you want to be informed for temperatures between 280 and 300 K, you probably should find another solution... Cheers, Bernhard

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October 13, 2016, 12:22		#22
sahmed Member Sheikh Ahmed Join Date: Dec 2015 Location: South Carolina, USA Posts: 88 Rep Power: 10	Hello Bernhard Thanks for your suggestion. In the recent chemical kinetic mechanism that I use, I have my Tlow as low as 200 for all the species. Even with that, I got janaf out of reach error msg. This has now been a global problem for all combustion solver users and there must be an inherent bug in the code. I think the developers should concentrate on it. Please share if you have any other suggestion. Thanks once again ~SFA

October 13, 2016, 16:13		#23
sheaker Senior Member Oskar Join Date: Nov 2015 Location: Poland Posts: 184 Rep Power: 10	Hello. As I know there is a bug in openFoam 2.1.1 which leads to nonphysical results: Cooling during compression. Here is example: https://www.youtube.com/watch?v=KA--7CpiCTA Unfortunately I can't find report of this bug. It is fixed in openFoam 2.2.1.

March 23, 2022, 17:47		#25
IFX21 New Member Aero_Cats! Join Date: Jul 2021 Location: Indonesia Posts: 7 Rep Power: 4	I solved this problem by reducing the timestep "deltaT" in "controlDict" files. The error disappears but still need some investigation on what really goes behind it