limited temperature in X cells

Bücherknopf · June 25, 2016, 15:20

Hello,
I have following problem: After I start my simulation I get the following warnings: "temperature corrections limited in X cells" and "temperature is set to minimum".
I created a treshold in a scene and looked in different time states, where these "bad" cells were. But they were always on different places.
I checked the mesh quality and there I got no invalid cells with the default settings.
Also my time step and my under relaxation factors are pretty low.
I dont understand why the temperature is limited ?

Can somebody explain it to me and maybe give me a solution to this problem?

marmot · June 26, 2016, 01:10

When solving the energy equation there is no numerical limit on temperature, thus in references you can find where you set a hard limit min/max, similar to passive scalar equation you also set a min/max.

When running steady-state this is not really an issue when you get this error message at the start up, most likely it goes away unless you have really bad cells and you have an energy source term or flux boundary near them

For transient it could mean you have a bad initial guess on temperature, say you initialize with 20C but have an inlet boundary with 500C,

Check your initial conditions
or run steady to get a flow/temperature field and than start transient,

Bücherknopf · June 26, 2016, 05:40

Thank you for your answer!

Unfortunately this warning doesnt go away and I get a problem with my combustion. It doesnt burn because the temperature is to low due to the limited temperature cells

.

I will try to run steady. (my current state is implicit unsteady)

What do you mean by checking my initial conditions?
Under continuum>initial conditions there are only a few selections like the initial pressure (~1bar) and my initial temperature(~300K).

marmot · June 27, 2016, 01:29

You can change the upper limit on the maximum temperature, although I think it is 2000 or 5000K by default,
Under continuum>reference values

Boiling is more my topic but perhaps it has more to do with the combustion model, rate, concentration, etc. that is the underlying problem not the min/max limits on temperature.

June 25, 2016, 15:20	limited temperature in X cells	#1
Bücherknopf New Member Join Date: May 2016 Posts: 17 Rep Power: 9	Hello, I have following problem: After I start my simulation I get the following warnings: "temperature corrections limited in X cells" and "temperature is set to minimum". I created a treshold in a scene and looked in different time states, where these "bad" cells were. But they were always on different places. I checked the mesh quality and there I got no invalid cells with the default settings. Also my time step and my under relaxation factors are pretty low. I dont understand why the temperature is limited ? Can somebody explain it to me and maybe give me a solution to this problem?

June 26, 2016, 01:10		#2
marmot Senior Member kevin alun Join Date: Sep 2011 Location: Germany Posts: 106 Rep Power: 14	When solving the energy equation there is no numerical limit on temperature, thus in references you can find where you set a hard limit min/max, similar to passive scalar equation you also set a min/max. When running steady-state this is not really an issue when you get this error message at the start up, most likely it goes away unless you have really bad cells and you have an energy source term or flux boundary near them For transient it could mean you have a bad initial guess on temperature, say you initialize with 20C but have an inlet boundary with 500C, Check your initial conditions or run steady to get a flow/temperature field and than start transient, Bücherknopf likes this.

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June 26, 2016, 05:40		#3
Bücherknopf New Member Join Date: May 2016 Posts: 17 Rep Power: 9	Thank you for your answer! Unfortunately this warning doesnt go away and I get a problem with my combustion. It doesnt burn because the temperature is to low due to the limited temperature cells . I will try to run steady. (my current state is implicit unsteady) What do you mean by checking my initial conditions? Under continuum>initial conditions there are only a few selections like the initial pressure (~1bar) and my initial temperature(~300K).

June 27, 2016, 01:29		#4
marmot Senior Member kevin alun Join Date: Sep 2011 Location: Germany Posts: 106 Rep Power: 14	You can change the upper limit on the maximum temperature, although I think it is 2000 or 5000K by default, Under continuum>reference values Boiling is more my topic but perhaps it has more to do with the combustion model, rate, concentration, etc. that is the underlying problem not the min/max limits on temperature.