Diverging and simulation run errors

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it is always diverging in some way like
“The solution diverged, please check your simulation setup. Divergence can also be caused by bad elements in the mesh. Such elements tend to exist near walls and sharp corners. Visually inspect your mesh to locate them and re-mesh with additional refinements in their vicinity. If you are confident about the mesh-quality, please reduce relaxation factors and use more conservative numerical schemes.”
“Temperature fields diverging”
when I am running a mach 1.5 wind tunnel with a CADed model. pls look at the project, as I only wanted to make some particle traces.

Reply ASAP.

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Hi, this is Fillia :slight_smile:

There are a few points I would like to mention:

  1. The Velocity inlet is > 800 m/s. This means the Mach number will be much bigger than 1 (Mach = U/c, where c is the speed of sound ~ 343 m/s). In general, the compressible solver handles up to 0.7-0.8 well, but a case with a Mach number close to 3 will probably fail.
  2. Have you checked the Reynolds number? I expect the ‘Laminar’ mode will have to be switched to a turbulent model.
  3. In contrast with the Incompressible analysis, the pressure outlet here is not Gauge. Try switching the input to 101325 Pa instead of 0 Pa.
  4. If the model is symmetric, you can simulate just half of it to reduce computation costs.
  5. The Domain is small for this kind of external aerodynamics simulation. Have a look at Figure 5 here: https://www.simscale.com/docs/tutorials/aerodynamic-simulation-vehicle/. You can use this as a reference.
  6. You can always check the mesh quality with this guide: https://www.simscale.com/knowledge-base/how-to-check-and-improve-mesh-quality/

Best regards,

By the way, if someone has a compressible case with a big Mach number that was successful, please provide the link, I would love to check it out :slightly_smiling_face:


Sup, Vir here (Full: Balvir Singh)

As a response to your first point, is there some way where I can simulate high mach speeds or is it impossible to do in Simscale?

Otherwise, I really appreciate the help you have put in here.

Happy CFDing, Balvir.

Hi @balvir_manj,

Please look at that reference in the forum:

I suggest, as Barry did, that you start to learn CFD with simpler cases.

Take care,


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