Simulation stopped after 1s.

lxlxlxt · February 14, 2014, 18:07

Hi all,

I'm using a Eulerian multifluid vof method to simulate two exothermic reactions. Since the reactants include polymers, the standard state enthalpy does not apply. So I set the standard state enthalpy to 0 and used a user-defined function for the energy source term. However, the simulation stops with the message as below:

temperature limited to 5.000000e+03 in 2 cells on zone 2 in domain 2
temperature limited to 5.000000e+03 in 122 cells on zone 2 in domain 3
temperature limited to 5.000000e+03 in 19 cells on zone 3 in domain 2
temperature limited to 5.000000e+03 in 152 cells on zone 3 in domain 3

Can anyone help?

andyj · February 18, 2014, 09:25

Hello !
Take a look at your formula. Are there any math logic errors, such as division by zero ect..

What software are you using?

What type of hardware are you using? Desktop..laptop?
What type of cpu? How much ram? Cpu temperature?

Is the reaction a chain reaction? A stepwise chain reaction? A chainwise reaction?
You say the reaction is exothermic, is the program seeing an unanticipated thermal runaway situation? Is the program seeing an out of control chain reaction?

What is the starting temperature? Initial pressure? Any catalysts? Any heat source?
Does the reaction run to completion or is it terminated?

andyj · February 18, 2014, 09:30

Is the reaction itself a known reaction? Is the reaction chemically possible?

andyj · February 18, 2014, 09:41

Do you have all your units correct in your chemical formula? Mixing degrees F,C, Kelvin? All your math units correct..all metric?
Is your chemical formula logical and correct?
Does your software specify any input parameters or automatically change any of your data entry to the programs default units?

Are you using a Linux cluster or running it at a supercomputer center?

andyj · February 18, 2014, 12:14

You may have experienced a thermal event involving hydrogen bond breakage in a chainwise manner.

lxlxlxt · February 18, 2014, 16:49

Thank you very much for your reply andyj. I'm using FLUENT running on a icore 5 desktop.

The reaction is terminated instead of reaching to completion. The units should be fine because the first 1s runs pretty similar from my matlab code. But I will double check that. The reactions are like:
A+B-->C
A+D-->E+F
And F is carbon dioxide gas generated. I put in the molecular weight and so forth because the fluent does not provide the database for these materials.

The reaction starts at 298.15K. No catalyst. And I defined a source term which gives the heat generated regarding to the conversion of B and D.

The reactions happen in a box which has wall as boundary conditions.

lxlxlxt · February 18, 2014, 16:53

Yes. It's a known chemical reaction.

February 14, 2014, 18:07	Simulation stopped after 1s.	#1
lxlxlxt New Member Michigan Join Date: Jan 2013 Posts: 10 Rep Power: 12	Hi all, I'm using a Eulerian multifluid vof method to simulate two exothermic reactions. Since the reactants include polymers, the standard state enthalpy does not apply. So I set the standard state enthalpy to 0 and used a user-defined function for the energy source term. However, the simulation stops with the message as below: temperature limited to 5.000000e+03 in 2 cells on zone 2 in domain 2 temperature limited to 5.000000e+03 in 122 cells on zone 2 in domain 3 temperature limited to 5.000000e+03 in 19 cells on zone 3 in domain 2 temperature limited to 5.000000e+03 in 152 cells on zone 3 in domain 3 Can anyone help?

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February 18, 2014, 09:25		#2
andyj Member Andy Jones Join Date: Sep 2010 Location: Columbus, Ohio Posts: 78 Rep Power: 15	Hello ! Take a look at your formula. Are there any math logic errors, such as division by zero ect.. What software are you using? What type of hardware are you using? Desktop..laptop? What type of cpu? How much ram? Cpu temperature? Is the reaction a chain reaction? A stepwise chain reaction? A chainwise reaction? You say the reaction is exothermic, is the program seeing an unanticipated thermal runaway situation? Is the program seeing an out of control chain reaction? What is the starting temperature? Initial pressure? Any catalysts? Any heat source? Does the reaction run to completion or is it terminated?

February 18, 2014, 09:30		#3
andyj Member Andy Jones Join Date: Sep 2010 Location: Columbus, Ohio Posts: 78 Rep Power: 15	Is the reaction itself a known reaction? Is the reaction chemically possible?

February 18, 2014, 09:41		#4
andyj Member Andy Jones Join Date: Sep 2010 Location: Columbus, Ohio Posts: 78 Rep Power: 15	Do you have all your units correct in your chemical formula? Mixing degrees F,C, Kelvin? All your math units correct..all metric? Is your chemical formula logical and correct? Does your software specify any input parameters or automatically change any of your data entry to the programs default units? Are you using a Linux cluster or running it at a supercomputer center?

February 18, 2014, 12:14		#5
andyj Member Andy Jones Join Date: Sep 2010 Location: Columbus, Ohio Posts: 78 Rep Power: 15	You may have experienced a thermal event involving hydrogen bond breakage in a chainwise manner.

February 18, 2014, 16:49		#6
lxlxlxt New Member Michigan Join Date: Jan 2013 Posts: 10 Rep Power: 12	Thank you very much for your reply andyj. I'm using FLUENT running on a icore 5 desktop. The reaction is terminated instead of reaching to completion. The units should be fine because the first 1s runs pretty similar from my matlab code. But I will double check that. The reactions are like: A+B-->C A+D-->E+F And F is carbon dioxide gas generated. I put in the molecular weight and so forth because the fluent does not provide the database for these materials. The reaction starts at 298.15K. No catalyst. And I defined a source term which gives the heat generated regarding to the conversion of B and D. The reactions happen in a box which has wall as boundary conditions.

February 18, 2014, 16:53		#7
lxlxlxt New Member Michigan Join Date: Jan 2013 Posts: 10 Rep Power: 12	Yes. It's a known chemical reaction.