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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013
Accepted Solution

CFD Motion Simulation Error

350 Views, 3 Replies
11-15-2013 07:53 AM

I've been trying to simulate the fluid motion within a gearbox. I have two helical gears with a prescribed angular motion. I continue to receive this error despite what I do:

 

"The Analysis has stopped because the Solver has exited unexpectedly."

 

The model meshes fine. After meshing and initializing, my output bar contains the following:

 

Control file processing complete

Check Out motion License: Successful

Authorization verified

Processing input...

2 Moving Solids found

Mesh input complete

Processing results input...

Results input complete

Processing BC input ...

Computing restart BC data...

Calculating BC data structures...

Calculate wall distance for 127754 fluid nodes

Wall distance calculation don in (0 + 1) seconds. Max distance = 1.63889

 

I've tried both refining and coarsening the mesh. I've modified the gap refinement properties. I've made the fluid and gear meshes uniform. My computer has 8GB if RAM and a Quaddro 4000 graphics card. Any thoughts as to what might be going wrong?

 

Thanks in advance

 

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Product Support
wildej
Posts: 850
Registered: ‎08-25-2011

Re: CFD Motion Simulation Error

11-18-2013 01:11 AM in reply to: ServusJeff

Hi,

 

This could be down to any number of things but here are a few suggestions.

 

1) Move the gears along their axis, out of the model in CAD and use linear + angluar in CFD. The linear part to move them back into position and the angular as before. This way you can turn on the mesh enhancement and achieve a nice boundary layer around the walls

2) You may wish to add refinement regions to the fluid within CAD. Perhaps around the walls if you have a leakage path and certainly where the teeth mesh

3) Give the solids  coarse mesh and just refine their surfaces. I would not use gap refinement here, as the gap dimensions are perpetually changing

4) Run with ADV 2 - typically the best for motion

5) Use a very small timestep - how many degrees of movement are you seeing with each step as it is now?

6) What fluid are you using? It might be worth switching the solver to compressible (under Physics), even though you are likely running with some incompressible fluid

 

Have you considered running a simpler 2D analysis initially, to help you get the right setup and an idea of the level of mesh you will require?

 

Kind regards,

Jon

 



Jon Wilde
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Product Support
wildej
Posts: 850
Registered: ‎08-25-2011

Re: CFD Motion Simulation Error

11-18-2013 03:24 AM in reply to: wildej

In addition: Please ensure you are running from a local drive and not remote/networked



Jon Wilde
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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013

Re: CFD Motion Simulation Error

11-18-2013 10:23 AM in reply to: wildej
Removing the gap refinement, adding a slightly finer region around the teeth mesh, running with ADV 2 and decreasing the timestep solved the problem. Thank you Jon for your help.
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