Divergence detected in AMG Solver:TEMPERATURE fsae body

bi_g · December 21, 2015, 13:34

Hi!

I'm working on 2d flow simulation of a fsae body. Those are some informations about setup:
Pressure based
Viscosity model: spalart allmaras - vorticity based
Density of an ideal gas
Boundary conditions: free - pressure far field with 101325 for gauge pressure and 0.4066 for mach number

After some iterations I have got the "Divergence detected in AMG Solver:TEMPERATURE". What can I do to solve this problem?

Thanks in advance,
Bianca

CeesH · December 21, 2015, 15:40

If you are running an ideal gas simulation, the simulation will keep track of the temperature too to abide PV = NRT. Of course, if you are not setting boundary conditions and so on for the temperature T, there may be some odd, unwanted effects of even divergence.

You can opt to simply initialize the simulation at a certain realistic temperature T, and disable the energy equation so the value of T remains fixed. This should remove such errors. Of course if you do not want an isothermal simulations, make sure all the conditions are set properly.

bi_g · December 25, 2015, 07:35

In this case I don't want a isothermal simulation so T can't be fixed.
I checked all the values on the setup and I think those are correct, because the values were used on a airfoil's simulation, and for the fsae body the conditions are almost the same.

December 21, 2015, 13:34	Divergence detected in AMG Solver:TEMPERATURE fsae body	#1
bi_g New Member BIANCA GIAROLA Join Date: Dec 2015 Posts: 5 Rep Power: 10	Hi! I'm working on 2d flow simulation of a fsae body. Those are some informations about setup: Pressure based Viscosity model: spalart allmaras - vorticity based Density of an ideal gas Boundary conditions: free - pressure far field with 101325 for gauge pressure and 0.4066 for mach number After some iterations I have got the "Divergence detected in AMG Solver:TEMPERATURE". What can I do to solve this problem? Thanks in advance, Bianca

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December 21, 2015, 15:40		#2
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	If you are running an ideal gas simulation, the simulation will keep track of the temperature too to abide PV = NRT. Of course, if you are not setting boundary conditions and so on for the temperature T, there may be some odd, unwanted effects of even divergence. You can opt to simply initialize the simulation at a certain realistic temperature T, and disable the energy equation so the value of T remains fixed. This should remove such errors. Of course if you do not want an isothermal simulations, make sure all the conditions are set properly.

December 25, 2015, 07:35		#3
bi_g New Member BIANCA GIAROLA Join Date: Dec 2015 Posts: 5 Rep Power: 10	In this case I don't want a isothermal simulation so T can't be fixed. I checked all the values on the setup and I think those are correct, because the values were used on a airfoil's simulation, and for the fsae body the conditions are almost the same.