[dunapkt]

Hi, currently I am working on a CFD simulation using a 2-stage stator-rotor model.

The mesh was generated using BladeGen and TurboGrid, and is designed to have one stator and two rotors with the same pitches. When I run the simulation with a configuration of 1 stator - 2 rotor - 1 stator - 2 rotor, the solver runs without problems and converges well.

However, when I set the value of "Passages to Model" to 4 on the stator and 8 on the rotor (i.e. 4 stator - 8 rotor - 4 stator - 8 rotor), the solver encounters an overflow error. I did not change anything except the number of blades, and I would like to know why this is happening.

Is there something that I need to change in the settings?

[zacko]

Did you define a massflow BC? And if yes, how did u set it? Total machine, or per passage? Maybe have a look there

[dunapkt]

Nope, I use pressure inlet&outlet condition.

[Gert-Jan]

Please provide a detailed description of the error, preferably the whole output file with all settings, or at least the last part starting from where everything went allright.

[dunapkt]

Error message is simple. Typical overflow error, but I don't know why. Still you need output file, I'll upload later.

[Gert-Jan]

Overflow can be caused by anything. For the context we need the output file.

[dunapkt]

Parallel run: Received message from follower
--------------------------------------------
Follower partition: 15
Follower routine : ErrAction
Leader location : Message Handler
Message label : 001100279
Message follows below - :

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Floating point exception: Overflow |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

Parallel run: Received message from follower
--------------------------------------------
Follower partition: 15
Follower routine : ErrAction
Leader location : Message Handler
Message label : 001100279
Message follows below - :

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine FPX: C_FPX_HANDLER |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine MESG_RETRIEVE. |
| Message: |
| Stopping the run due to error(s) reported above |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+

End of solution stage.

Due to file size limitaion, I upload only error messages

[Gert-Jan]

It is good that you upload all the errors, but then we are still missing the context. In this way it is meaningless. Sorry.
You can upload the output file in the "Go Advanced" menu, in the bottom of your screen.

[dunapkt]

I see, here is output file.

[Gert-Jan]

- Better start reading this: https://www.cfd-online.com/Wiki/Ansys_FAQ
- You see that your Maximum mach number is inceasing continuously. This should be a red flag for you. You better stop the calculation before it crashes and look what goes wrong. Best create multiple back ups and open these in Post to see how things develop. From that you learn what goes wrong and what precautions you have to take.
- I see you have no initial guess. Why not? You better start with a simple setup at low speed, and small dp, then restart over and over with tougher settings till you get what you want.
- Bottomline: with this calculation it looks like you are trying to hit the roof in one go. That is not how it works. CFX is robust and forgiven, but it does not eat everything in one step by default. Treat it in a more gentle way.