[dlugi91]

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.

This is image of my model with marked faces in which i have problem.

[ghorrocks]

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

[dlugi91]

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]

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

[dlugi91]

There is photo's, output file and error details:

[ghorrocks]

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]

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]

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]

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

[ghorrocks]

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]

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]

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]

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]

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

[Rolandy]

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]

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

[Rolandy]

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]

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

[dlugi91]

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