Negative temperature

anjantula · February 20, 2010, 21:21

Hello ,

I am working on combustion of methane , where there are 50 species and 400 reactions . for initial solution i use non premix / partially mix pdf models and after wards i use edc models . but when i import my mechanism file and thermo file and enable the edc model and start the iterations

i get this sort of error on the very first iteration .

Error: ISAT reaction rate: Temperature = -7274.0K
Error Object: ()

Mica · July 13, 2011, 09:59

Hello,

did you solve the problem? I'v pretty much the same, so it would be very nice to know how to handle it.

Thanks in advance!!

MikeTichondrius · July 13, 2011, 10:08

I've run into this problem while running a non-premixed turbulent combustion case...What I did was to set upper and lower limits for temperature closer to what my problem would present, in the Solution Controls tab. (In my case, I set the lower limit to 200K and the upper limit to something like 2500K, yours may differ of course). I did work in the end.

Mica · July 13, 2011, 10:48

Thanks for your help Mike!
Unfortunately my problem seems to be a little more besetting... I set Temperature limits to 250 and 1600K but its still the same...

Primitive Error at Node 1: ISAT reaction rate: Temperature = -1248.0K

Anybody that had a similar problem and knows a solution?

much thanks in advance!!!

jamesshocker · January 2, 2014, 21:49

Hi,

I've encountered a similar problem where a heat source leads to negative temperatures in the system which is not physically sound. I also noticed that setting the lower temperature limit to say 300K does not limit the static temperature to 300K but the total temperature. Any further insights would be welcome.

February 20, 2010, 21:21	Negative temperature	#1
anjantula New Member Anjan Join Date: Jan 2010 Posts: 2 Rep Power: 0	Hello , I am working on combustion of methane , where there are 50 species and 400 reactions . for initial solution i use non premix / partially mix pdf models and after wards i use edc models . but when i import my mechanism file and thermo file and enable the edc model and start the iterations i get this sort of error on the very first iteration . Error: ISAT reaction rate: Temperature = -7274.0K Error Object: ()

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Calculation of the Governing Equations	Mihail	CFX	7	September 7, 2014 06:27
[blockMesh] BlockMesh FOAM warning	gaottino	OpenFOAM Meshing & Mesh Conversion	7	July 19, 2010 14:11
help,why the negative energy source does'nt make the temperature decrease, thank you!	hunter	FLUENT	6	May 12, 2010 17:39
temperature going negative behind a bluff body	Sourabh	Phoenics	6	December 1, 2007 18:50
[blockMesh] Axisymmetrical mesh	Rasmus Gjesing (Gjesing)	OpenFOAM Meshing & Mesh Conversion	10	April 2, 2007 14:00

July 13, 2011, 09:59		#2
Mica New Member Join Date: Jul 2011 Posts: 5 Rep Power: 14	Hello, did you solve the problem? I'v pretty much the same, so it would be very nice to know how to handle it. Thanks in advance!!

July 13, 2011, 10:08		#3
MikeTichondrius New Member Miguel Graça Join Date: Feb 2011 Posts: 4 Rep Power: 15	I've run into this problem while running a non-premixed turbulent combustion case...What I did was to set upper and lower limits for temperature closer to what my problem would present, in the Solution Controls tab. (In my case, I set the lower limit to 200K and the upper limit to something like 2500K, yours may differ of course). I did work in the end.

July 13, 2011, 10:48		#4
Mica New Member Join Date: Jul 2011 Posts: 5 Rep Power: 14	Thanks for your help Mike! Unfortunately my problem seems to be a little more besetting... I set Temperature limits to 250 and 1600K but its still the same... Primitive Error at Node 1: ISAT reaction rate: Temperature = -1248.0K Anybody that had a similar problem and knows a solution? much thanks in advance!!!

January 2, 2014, 21:49		#5
jamesshocker New Member James Evon D'Souza Join Date: Jan 2014 Location: Singapore Posts: 1 Rep Power: 0	Hi, I've encountered a similar problem where a heat source leads to negative temperatures in the system which is not physically sound. I also noticed that setting the lower temperature limit to say 300K does not limit the static temperature to 300K but the total temperature. Any further insights would be welcome.