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CFX: ERROR #002100080: Significant Normal Component or MESH is moving

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Old   August 27, 2012, 14:51
Question CFX: ERROR #002100080: Significant Normal Component or MESH is moving
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m0h
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Dear Sirs,

I have a problem with ANSYS CFX. I am trying to do an multiphase analysis with water and air in a rotating default domain. In the attachment you can find the detailed problem description and the Step file with the geometry.

OilPan.pdf http://dl.dropbox.com/u/66722906/Oil%20Pan.pdf
OilPan.zip (STP File) http://dl.dropbox.com/u/66722906/CFD_Oil_Pan.zip

I would appreciate your support in terms of my problem. Please find the error code below:

================================================== ====================
OUTER LOOP ITERATION = 1 CPU SECONDS = 2.293E+00

+--------------------------------------------------------------------+
| ERROR #002100080 has occurred in subroutine CHECK_NORMV. |
| Message: |
| The specified velocity vector on the boundary patch |
| |
| Rohr |
| |
| has a significant normal component at one or more faces. One of |
| these face locations is |
| |
| (x,y,z) = ( 2.31316E-01,-1.46685E-02, 2.43947E-03). |
| |
| The angle between the specified velocity and the element surface is|
| 81.624 degrees at this face. This is considered an error because |
| it implies that the mesh is moving. The following are possible |
| reasons for the error message: |
| 1. There is a setup error; for example, an incorrect axis of |
| rotation. |
| 2. There may be a meshing problem; for example, the nodes on a |
| rotating surface might not lie on the surface of revolution. |
| 3. The boundary is curved and the mesh is very coarse. In this |
| case, you may modify the tolerance by increasing the |
| expert parameter 'tangential vector tolerance wall' |
| from its default of 20 degrees. |
+--------------------------------------------------------------------+

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Old   August 27, 2012, 19:47
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Glenn Horrocks
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Does the scoop pipe rotate with the domain? Or is it meant to be stationary?

I take it there are 4 scoop pipes in the full domain.
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Old   August 28, 2012, 03:44
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Hi ghorrocks, thank you for your effort.

No, the scoop pipe stands still. The whole domain rotates besides of the scoop pipe. Thats why I have chosen the boundary "counter rotating wall" in CFX. In the ansys help i found that the selected geometry rotates with -omega*r. So the absolut velocity will be zero.

The next step of the analysis will be to model the inlet geometry of the pipe because until know this is neglected. I just want to see what is the seperation angle of the water caused from the scoop pipe.

The number of scoop pipes depends on the required discharge of oil. In this case there are 4 scoop pipes. Thats why i have chosen a fourth of the whole.

Please find the sketch in the attachment. I hope this makes the system more clear.

Thank you in advance and best regards from Austria.
Attached Files
File Type: pdf Oil_Pan_Sketch.pdf (31.3 KB, 52 views)
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Old   August 28, 2012, 08:21
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I see - in that case you have taken the wrong approach. If the scoop pipe is still then it needs to go into a stationary frame of reference, with the rotating bit in a rotating frame of reference, and are connected by a GGI. Have a look at the rotor/stator example for how to do this.

Is there 1 scoop pipe or more than 1?
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Old   August 28, 2012, 11:00
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hi ghorrocks,

ok i will check this turorial. I used a fourth of the whole for my calculation model (90degrees) because i assume 4 scoop pipes on the whole system. To safe calcualtion time and mesh elements I used a fourth piece. So in my calculation model there is one, but in reality on 360 there are 4.

Thanks, i will keep you updated.
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Old   August 28, 2012, 20:31
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OK, so you have 4 scoop pipes and I think it was 10 paddles. So on the stationary frame of reference you can use 1/4 of the model, in the outer rotating frame of reference you can use 1/10 symmetry. This will make your simulation smaller and easier to manage.
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Old   August 29, 2012, 02:34
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Good morging everybody,

ghorrocks, yesterday i did the tutorial of the Rotor Stator (axial Turbine with TURBO GRID import). In principle now I understand what I have to do. But my question is how to set up the model. In the tutorial i have seen that there are two seperate domains used and connected via "Domain Interface". My Problem is, that the scoop pipe is inside of the Oil pan. Where do I have to define the cut (where do I have to create the interface) to be able to create two seperate 3D models and then two domains?

The scoop pipe is just a cylindical cutout out of the oil pan volume....

Thank you in advance for you help
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Old   August 29, 2012, 08:14
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Hello once again,

I think now i got it. I did the wrong tutorial. there is a seconed one with a mixer. today evening I will do this one. As far as I found out in the help the problem is that i have not done 2 different domains.

I will keep you updated. Thank you for your support.
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