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-   -   Solver can not produce result (http://www.cfd-online.com/Forums/cfx/117788-solver-can-not-produce-result.html)

dlugi91 May 15, 2013 05:06

Solver can not produce result
 
Hi All,
I am working on air flow over wing (subsonic and supersonic) and when I start solver, it worked few seconds and i see ,that message: "The solver failed with a non-zero exit code of: 2". After i can not edit setup because CFX-Pre have some error. When i try resolve this issue i saw that air does not flow through the connection of solids, which make up the model. But i don't know how connect this solids to air flow through them.
http://imageshack.us/photo/my-images...ztytuurzd.png/
This is image of my model with marked faces in which i have problem.

ghorrocks May 15, 2013 06:31

You either need to remesh to make the mesh regions join up or connect them with GGI interfaces.

dlugi91 May 15, 2013 15:54

I connect this regions with GGI interface and Solver start but in iteration 46 the same error show up. I don't know if I set properly this interface or it's diffferent issue. If i post details of this error from Ansys or output from Solver it will help in the aid?

ghorrocks May 15, 2013 18:24

Please post your output file as an attachment, and some images of what you are seeing.

dlugi91 May 17, 2013 09:39

1 Attachment(s)
There is photo's, output file and error details:
http://imageshack.us/photo/my-images/585/mesh.jpg/
http://imageshack.us/a/img248/3091/geometrys.jpg
http://imageshack.us/a/img442/6810/errormf.jpg

ghorrocks May 17, 2013 19:07

Also what is the geometry? I have no idea what those blocks are. Some explanation would be useful.

You have had a divide by zero error. See this FAQ: http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

dlugi91 May 19, 2013 07:55

I want to simulate air flow over wing with subsonic and supersonic speed. I choose NACA 0009 profile to simple simulation. Midle block on geometry is space over a wing, left and right blocks are space in a front of wing and behind wing. My simulation is very similar to example in cfx tutorial (charper 10), so I modeled my geometry on this example. I mesh geometri and set boundaries like in this example and when I start solver for supersonic flow I see error, I wrote about early. So I make wrong geometry or mesh? Or I set wrong boundaries.

Rolandy May 19, 2013 10:46

Hi,
Your analysis relate to external flow field. In the case as you describe, if you surpress the solid the geometry or mesh is commenly no wrong. Notice your boundaries and interface setting.

dlugi91 May 19, 2013 16:09

Settings of boundaries and interfaces are on output file in post #5.

ghorrocks May 19, 2013 19:33

To model this supersonic you will probably need local timescale factor (using about 5.0) to start the convergence along, and once that is going switch back to phyisical time scale. And the physical time scale will need to be very small.

And mesh quality will be important. If the mesh adjacent to the airfoil is not nice you will have problems with convergence.

Rolandy May 21, 2013 01:59

Your FLOW REGIME:
Option = Supersonic
and your MATERIAL: Air Ideal Gas
The Air Ideal Gas is an incompressible fluid, for supersonic flow, you must choose the "Air at 25C".
please try this....

ghorrocks May 21, 2013 19:18

Sorry Roland, you got them the wrong way round. "Air at 25C" is an incompressible fluid. You need to select "Air ideal gas" to active the compressible flow model.

Rolandy May 21, 2013 23:14

Thanks ghorrocks, I have a wrong theory for ideal gas. Thank you!
But why dose the dlugi91's simulation have a non-linear P-Mass? Should he change the symmetrical bounderies to openning?

ghorrocks May 22, 2013 05:57

Where does it say a non-linear P-Mass?

Rolandy May 23, 2013 00:13

OUTER LOOP ITERATION = 44 CPU SECONDS = 4.967E+01
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+
| U-Mom | 0.28 | 1.6E-04 | 8.3E-03 | 2.8E-02 OK|
| V-Mom | 0.23 | 6.2E-04 | 2.5E-02 | 5.8E-02 OK|
| W-Mom | 0.23 | 5.0E-03 | 8.3E-02 | 4.3E-02 OK|
| P-Mass | 0.01 | 2.9E-05 | 2.5E-03 | 8.6 4.9E+02 F |

ghorrocks May 23, 2013 06:31

This is just non-cenvergence of the P-Mass equation. It means smaller time steps and/or better mesh quality is required.

Rolandy May 23, 2013 08:58

Even more about the case. I met a situation, the time steps and mesh were correct, but the W-Mom or p-mass was non-linear. When I reseted the inlet boundary, the problem was resolved.

ghorrocks May 24, 2013 06:16

Have you read the section in the CFX documentation about setting up boundary conditions and obtaining convergence? This discusses all these issues.

dlugi91 May 30, 2013 09:13

I finish my simulation with using Fluent and 2D model. Thanks all for help :)


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