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-   -   Axi-symmetric modeling? (http://www.cfd-online.com/Forums/star-ccm/64210-axi-symmetric-modeling.html)

MaxCFM May 3, 2009 11:59

Axi-symmetric modeling?
 
I have a 3D model (nozzle) that I'd like to convert into an axi-symmetric model. What is the simplest way to do this? The help files have not been much help. I've tried converting the 3D mesh into 2D but when I try to change the X-axis boundary type to an axis boundary there is no axis type in the drop-down box. There is no geometry located in -Y. Model type is axi-symmetric in physics continuum. If I select symmetry it treats it as 2D.

Apparently I can't remesh a 2D model either. That makes it a real pain. Is this correct?

Thank you

bernarde June 1, 2009 05:22

Hi

I have been looking at this type of problem as well. As far as I understand you are not able to model an axisymmetric model as purly a 2D model. A pure 2D model in Star-CCM+ does not allow you to specify any property out of the plane (such as a tangential velocity for swirl in a pipe).

To achieve an axysimmetric model you have to model a wedge, and then make use of periodic boundaries. The angle of the wedge must be such to ensure a good aspect ratio of the cells on the axis, ie you cannot have a wedge that is too sharp. The periodic boundaries must also be indentical in shape.

I found this restriction quite frustrating. I would have liked to be able to construct a 2D model, and then specify an axis, and be able to specify properties perpendiculat to then plane, that are axisymmetric about this axis. I suspect this is what you are also aiming for?

Regards

MaxCFM June 1, 2009 09:24

Yes, that is what I desire. In my limited experience this is one area where Fluent beats Star-CCM+ hands down.


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