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-   -   Periodic & Symmetric Boundaries (http://www.cfd-online.com/Forums/fluent/48536-periodic-symmetric-boundaries.html)

Marc June 18, 2008 15:36

Periodic & Symmetric Boundaries
 
Hi everyone,

My current research makes use of a symmetry boundary condition down the centre of my geometry. I have now decided that I would like to make an array of my geometry, using periodic boundary conditions.

My original attempts tried to put a periodic boundary condition on one-half of my model with a symmetric boundary condition down the centre. It seems that this does not work.

I get the impression that in order to enforce periodic boundary conditions, I need to hard link faces that are opposite one-another. However, my geometry on the back face and the 'centre' is not the same and as a result, I do not want the mesh to be the same.

Is there any way around this?

red lemon June 19, 2008 14:28

Re: Periodic & Symmetric Boundaries
 
use non conformal periodics. Can only switch on in Fluent in the TUI. Set up as interfaces then create periodics in fluent TUI.

Marc June 19, 2008 22:56

Re: Periodic & Symmetric Boundaries
 
How do I make non conformal periodics? Do I use "define/boundary conditions/modify-zones" and choose "make-periodic"?

red lemon June 20, 2008 06:04

Re: Periodic & Symmetric Boundaries
 
ok.

"grid>modify zone>make periodic" creates a conformal periodic zone.

"define>boundary conditions>modify zones>make periodic" also creates a conformal periodic zone.

"define>grid interfaces>make-periodic" creates a non conformal periodic. The faces should be of type interface first. An angle or displacement is needed here depending on whether it rotational or translational resp. I think they are then listed in the grid interfaces panel.

Gambit/Fluent only understand default "periodic zones" if they are hard linked or node matched face sets. Gambit will not allow export of a none linked face mesh set that have not been previously hard linked but defined as a periodic zone.

A single periodic zone is made up of both sets of faces.


Marc June 20, 2008 12:26

Re: Periodic & Symmetric Boundaries
 
Thanks! Having some problems with this, but I think it's on my end. Will play around with it a bit.

hhh August 30, 2012 09:09

boundary condition (symmetry vs periodic doubt)
 
Dear friends,
i am doing 3D wing analysis, i have doubt on boundary conditions in fluent ie both symmetry and periodic, anybody have the answer please let me know briefly,for what kind of purpose to use symmetry & periodic boundary conditions, please tell any example with problem.


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