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Old   September 19, 2022, 18:11
Default Divergence Error
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CleverBoy
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Hello everybody,


I am trying to simulate a re-entry case. When I start the analysis it diverge and stop the simulation at iteration 0 with following error:


Code:
Error in "void CSolver::SetResidual_RMS(const CGeometry*, const CConfig*)": 
-------------------------------------------------------------------------
SU2 has diverged (NaN detected).

What is the reason of this?
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Old   September 20, 2022, 04:13
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This can really be anything, from a bad mesh to a wrong setup or solver settings that are not strict enough.

The first thing to check is the mesh. Make sure that the mesh quality is good. Also, the combination of boundary conditions and the placement of inlets, outlets and far field is quite important. For instance, if the outlet is too close to your object of interest, there can be some unwanted interference that can also prevent convergence.

Which solver are you using? The regular compressible RANS or NS, or the NEMO solver?

Can you post a picture of your geometry+boundary conditions?
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Old   September 20, 2022, 06:19
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Quote:
Originally Posted by bigfootedrockmidget View Post
This can really be anything, from a bad mesh to a wrong setup or solver settings that are not strict enough.

The first thing to check is the mesh. Make sure that the mesh quality is good. Also, the combination of boundary conditions and the placement of inlets, outlets and far field is quite important. For instance, if the outlet is too close to your object of interest, there can be some unwanted interference that can also prevent convergence.

Which solver are you using? The regular compressible RANS or NS, or the NEMO solver?

Can you post a picture of your geometry+boundary conditions?

I am using RANS, SST V2003m and after that I will try it with NEMO. When I try to run it with SA it goes up to 70 iteration and gives the same error.

I am using GMSH and I am super new to almost everything about it. I import the geometry from SolidWorks.
As you said probably something's wrong with mesh or BCs. I will post the .cfg and .geo if you want.

I can try meshing and setting up the boundary conditions with Ansys Meshing tonight.
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Last edited by CleverBoy; September 25, 2022 at 16:22.
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Old   September 21, 2022, 12:18
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Wally Maier
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Nemo will not work with turbulence as of right now.
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Old   September 21, 2022, 18:04
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Quote:
Originally Posted by wallym View Post
Nemo will not work with turbulence as of right now.
Oh, that's sad to hear. I read the article "SU2-NEMO: An Open-Source Framework for High-Mach Nonequilibrium Multi-Species Flows" and there, it was written that NEMO has SA model within the framework. Does it not work properly? or was it removed?
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Old   September 21, 2022, 18:30
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Rather, the NEMO code that exists in the develop branch does not have turbulence. The NEMO with turbulence branch just underwent large changes to allow for the use of the SST stage. The branch (feature_NEMO_turb) *should/may* work, but is undergoing additional testing before its put into the develop branch.
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