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-   -   Cylindrical Symmetry (http://www.cfd-online.com/Forums/cfx/107252-cylindrical-symmetry.html)

 VikramR September 21, 2012 11:07

Cylindrical Symmetry

Hello CFX users, I have a reactor with cylindrical symmetry. How do I solve the problem on only one plane of theta?. I know this is to be done using slice material but when I slice an arc that does not form from the center of the cylinder.

 Trues September 21, 2012 11:30

what program was used to make the geometry? Do you have the ability to modify that geometry, or was it given to you?

For me, if it was given to me as a full cylinder (for example) in ProE, I'd much rather make the cyclic cut in ProE than in DesignModeler

 VikramR September 21, 2012 11:52

I made the geometry myself in DesignModeler

 Trues September 21, 2012 13:48

A picture would speak 1000 words.

If I'm picturing your issue correctly, which it's possible I'm not, you're having trouble getting the slice to go through the centerline of the cylinder? Why don't you add a new coordinate system at the centerline on the face of your cylindrical geometry and sketch your slice so that you can constrain it to the geometry centerline?

 VikramR September 21, 2012 13:52

In the sliced material, when I give the inward thickness on extrude to be less than 2 cm( which is the radius of the cylinder), it accepts. But when I want it to be 2cm it wont accept the value. Does it make more sense now?

 Trues September 21, 2012 13:56

sounds like you're trying to slice a wedge out of your cylinder, right? Your sketch needs to be opened. Don't draw the arc, just the two radials, like an open V. Is this what you're having trouble with?

 VikramR September 21, 2012 14:00

Yeah, you figured it out right but,
I could draw the outer edge but not the one closer to the center i.e, i can not draw the sharp edge.

 Trues September 21, 2012 14:11

The only other thing i can say is try with thin surface set as no. I'd have to see what you're talking about to help any further

 evcelica September 21, 2012 19:44

Dont slice or cut your geometry. Just use TOOLS > SYMMETRY. Set to two planes, have one plane be whatever plane cuts through the center, and create another plane rotated 1 degrees or so off that one.

 VikramR September 24, 2012 20:12

Thank you very much, I used symmetry and it worked perfectly.

 evcelica September 25, 2012 03:43

No problem. Yeah, the symmetry tool works very well for symmetry :D

 brunoc September 25, 2012 06:50

Also, remember to set periodicity in ANSYS Meshing so that you get a 1:1 mesh connection when setting your periodic BCs in CFX. GGI interfaces do work pretty well, but by using a 1:1 interface you save memory and CPU time.

Cheers

 ghorrocks September 25, 2012 08:03

If the simulation has no swirl then use symmetry planes on the top and bottom faces. If the simulation has swirl then use periodic boundaries.

BTW: This thread is an FAQ - http://www.cfd-online.com/Wiki/Ansys..._simulation.3F

You might as well just point people to the FAQ. If you think the FAQ is wrong or could be improved then feel free to edit it.

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