[residual]

Helo All,

I have been running a cfd in CFX for a fan case. the mesh for volute and impeller are generated by ICEM.
in CFX-pre it looks fine and inlet, outlet, wall configurations and interface between impeller and volute is set aswell.
But it doesnt complete any iteration under parallel processing and Double precision and only 13 iterations in series processing.
I have tried stator and frozen rotor both options in defining interface from impeller outlet to volute inlet.


I think i have set the physical models appropriately.
below is the error message am obtaining.

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

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

+--------------------------------------------------------------------+
| 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.

+--------------------------------------------------------------------+
| The following user files have been saved in the directory |
| D:\Xianghui_Cases\case_2_all_files\FlowRate_runs\d p_FrozenRotor\s- |
| etup_1_001: |
| |
| mon |
+--------------------------------------------------------------------+


+--------------------------------------------------------------------+
| Warning! |
| |
| After waiting for 60 seconds, 1 solver manager process(es) appear |
| not to have noticed that this run has ended. You may get errors |
| removing some files if they are still open in the solver manager. |
+--------------------------------------------------------------------+


This run of the ANSYS CFX Solver has finished.
"


I have been stuck in this for almost a week and admire anyone with a little assistance.

Thanks.

[Gert-Jan]

It can be anything. Most likely your boundary conditions are not correct.
I would suggest to run serial, make a few backups during those 13 iterations, and see how it looks like in Post. Probably, you'll find the problem quite fast.


Regs Gert-Jan

[ghorrocks]

If you are getting a difference between serial and parallel then a partition boundary is in a bad place. Change the partitioning (maybe use recursive bisection) to move the partition boundaries away from the sensitive areas.

But if the serial run diverges with a floating point error then you have a problem with numerical stability. This is a FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

[residual]

Originally Posted by Gert-Jan

It can be anything. Most likely your boundary conditions are not correct.
I would suggest to run serial, make a few backups during those 13 iterations, and see how it looks like in Post. Probably, you'll find the problem quite fast.


Regs Gert-Jan

Thanks, I have specified this run under mass flow rate and inlet pressure.
I have tried more that 20 runs increasing and decreasing mass flow rate to very low and very high values. but it does not make any difference.

[residual]

Originally Posted by ghorrocks

If you are getting a difference between serial and parallel then a partition boundary is in a bad place. Change the partitioning (maybe use recursive bisection) to move the partition boundaries away from the sensitive areas.

But if the serial run diverges with a floating point error then you have a problem with numerical stability. This is a FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

Thanks,

I have tried the first instruction. I ended up getting an error saying
*** INSUFFICIENT MEMORY ALLOCATED *** |
| |
| ACTION REQUIRED : Increase the integer stack memory size.

And i have increased the stack memory upto 1.2. still i dont see any deviation from earlier warning

[Gert-Jan]

Originally Posted by residual

Thanks, I have specified this run under mass flow rate and inlet pressure.
I have tried more that 20 runs increasing and decreasing mass flow rate to very low and very high values. but it does not make any difference.

Are you convinced that the dimensions are correct? Sometimes users draw a geometry in meters and import in it mm, or the other way around.



And what do the back ups tell you?

[residual]

Originally Posted by Gert-Jan

Are you convinced that the dimensions are correct? Sometimes users draw a geometry in meters and import in it mm, or the other way around.



And what do the back ups tell you?

Thanks for response,

Yeah i checked with the units and backups seems fine with what i understand.