Three Gas Flow Mixing Problem

Yu Yang · March 22, 2018, 11:28

Hi everyone! I'm a beginner level user of Fluent. I met a problem when I'm trying to simulate the mixing of three different Gas flows from separate inlets. I have no problem when I tried to solve the mixing of 2 Gas flows. But when I trying to add in one more flow, the error message like "turbulent viscosity limited to viscosity ration of e.000000e+05" pops out every time and the model fails to converge.
I was wondering if the species model I selected is wrong. I select the Species Transport. Should I use the PDF Transport or what?
Please help me with this problem. I will be really appreciative. Thanks!!!

LuckyTran · March 22, 2018, 18:36

Use the same transport model for the 2 gas case.

Check your material properties and initial guess.

For debugging purposes, you can use a 3 gas setup but set all the BC's or the 3rd species to 0. What I mean is, use a 3 species transport model on your two inlet problem. This should give identical result to 2 species case with 2 inlets.

Yu Yang · March 23, 2018, 16:17

Thank you for your reply Lucky Tran! I have tried the debugging method you suggested by setting 3 species coming in from 2 inlets. This kind of set up also fails to converge after several iterations. But the error message I frequently get this time is "temperature limited to 1.000000e+00 in xxxx cells on zone xx in domain xx". Do you know what else I can do to resolve this problem or what could I do for simplify my case? Thank you very much for your help!

Yu Yang · March 26, 2018, 09:57

Please help me! Thank you so much!

March 22, 2018, 11:28	Three Gas Flow Mixing Problem	#1
Yu Yang New Member Yu Yang Join Date: Mar 2018 Posts: 4 Rep Power: 8	Hi everyone! I'm a beginner level user of Fluent. I met a problem when I'm trying to simulate the mixing of three different Gas flows from separate inlets. I have no problem when I tried to solve the mixing of 2 Gas flows. But when I trying to add in one more flow, the error message like "turbulent viscosity limited to viscosity ration of e.000000e+05" pops out every time and the model fails to converge. I was wondering if the species model I selected is wrong. I select the Species Transport. Should I use the PDF Transport or what? Please help me with this problem. I will be really appreciative. Thanks!!!

March 22, 2018, 18:36		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	Use the same transport model for the 2 gas case. Check your material properties and initial guess. For debugging purposes, you can use a 3 gas setup but set all the BC's or the 3rd species to 0. What I mean is, use a 3 species transport model on your two inlet problem. This should give identical result to 2 species case with 2 inlets. Yu Yang likes this.

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March 23, 2018, 16:17		#3
Yu Yang New Member Yu Yang Join Date: Mar 2018 Posts: 4 Rep Power: 8	Thank you for your reply Lucky Tran! I have tried the debugging method you suggested by setting 3 species coming in from 2 inlets. This kind of set up also fails to converge after several iterations. But the error message I frequently get this time is "temperature limited to 1.000000e+00 in xxxx cells on zone xx in domain xx". Do you know what else I can do to resolve this problem or what could I do for simplify my case? Thank you very much for your help!

March 26, 2018, 09:57		#4
Yu Yang New Member Yu Yang Join Date: Mar 2018 Posts: 4 Rep Power: 8	Please help me! Thank you so much!