Maximum Iteration exceeded error

I’ve been designing a concentric crossflow exhaust gas heat exchanger and I am getting the following error whenever I try to run the model.
"Maximum number of iterations exceeded when calculating temperature from a thermodynamic potential. "
My mesh appears to be fine but I may be missing something, I realize the temperature difference is large but when I did the calculations on it by hand it should still give me an answer.
here is my project for reference:

Hi there!

Did you already try the suggestions given in this page?

If you did, please let me know what you tried so my investigation is easier and faster!

Hello there, I have made the following changes:

  1. Changed my geometries to have much smaller velocities
  2. Used a level 8 fine mesh
  3. Made sure that the fluid equations were correct.
    and I still am getting the same error
    Here is my updated version:
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Hi, and thanks for your reply.

I am suspicious if your “Galden HT230” material. Did you double check the properties? Have you used them before?

Ya I checked the properties and fixed the dynamic viscosity.

Here are the properties of this specific oil (2nd to last column)
Here is my new simulation but it still gives the same error.

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From having a look at the solver log, the simulation fails because one of the flow regions reaches negative temperatures:

This is likely related to some faces that are unnecessarily complex for the third flow region:

You may find these faces close to the inlet and outlet faces of the air domain. I’d suggest cleaning up the CAD model around those regions. See this thread for more info: Most Common CAD Issues with an Example


Appreciate the advice! Would you say that using the delete gap and face tool in CAD mode would be enough or do I have to go back and adjust the original model (adding fillets etc…).