rhoSimpleFoam Help

maike151 · October 21, 2020, 04:16

Hello everyone,

I am trying to do a rather simple test case where a hot air stream in a pipe like shape is at some point mixed with a colder air stream and I want to find out the temperature at the outlet.

The Mach numbers are very small (<= 0.01), thus I probably would not need to use a compressible solver. However, I need the temperature field and I didn't find such an incompressible solver.

My problem is that the simulation does not converge. I tried a lot of relaxation factors and boundary condition combinations but nothing seems to help. I also tried to start with very low relaxation factors and increased them after about 100.000 iterations each, still no convergence.

Maybe somebody has an idea what I'm doing wrong.

You can find the case here: https://www.dropbox.com/sh/xlpwf1had...z_CzdpB6a?dl=0

Thank you

Maike

maike151 · October 22, 2020, 09:04

If anybody wondered.. I fixed the problem by simulating with turbulence (RAS - kEpsilon) and starting off with very low relaxation factors (0.01) for every variable except U (0.8).

October 21, 2020, 04:16	rhoSimpleFoam Help	#1
maike151 New Member Join Date: Mar 2020 Posts: 18 Rep Power: 6	Hello everyone, I am trying to do a rather simple test case where a hot air stream in a pipe like shape is at some point mixed with a colder air stream and I want to find out the temperature at the outlet. The Mach numbers are very small (<= 0.01), thus I probably would not need to use a compressible solver. However, I need the temperature field and I didn't find such an incompressible solver. My problem is that the simulation does not converge. I tried a lot of relaxation factors and boundary condition combinations but nothing seems to help. I also tried to start with very low relaxation factors and increased them after about 100.000 iterations each, still no convergence. Maybe somebody has an idea what I'm doing wrong. You can find the case here: https://www.dropbox.com/sh/xlpwf1had...z_CzdpB6a?dl=0 Thank you Maike

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October 22, 2020, 09:04		#2
maike151 New Member Join Date: Mar 2020 Posts: 18 Rep Power: 6	If anybody wondered.. I fixed the problem by simulating with turbulence (RAS - kEpsilon) and starting off with very low relaxation factors (0.01) for every variable except U (0.8).