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-   -   Periodic Vs symmetry Boundary conditions (https://www.cfd-online.com/Forums/cfx/118918-periodic-vs-symmetry-boundary-conditions.html)

Amoul June 6, 2013 12:46
Periodic Vs symmetry Boundary conditions
 
Hello,
I would like to know the difference between periodic and symmetry boundary conditions? :confused:
Thanks,

vishal.indomitable June 6, 2013 14:19
Periodicity means that the thing or part is repeating itself.
Eg: You can take single blade of a turbine runner and apply periodicity.

Symmetry type boundary condition is applied if the geometry is exactly same about a plane. Ex: If you cut any body into exact half and place that body in front of a mirror, you are able to visualise the complete picture of the body.

ghorrocks June 6, 2013 19:25
You really should understand the mathematical basis of these boundary conditions. Read any CFD textbook for a description of this in detail, but in short a symmetry boundary has zero normal gradient for all variables except the normal velocity which is zero; and a periodic boundary just maps the values from one boundary across to another.

pavitran June 7, 2013 00:02
Hi
 
Quote:
Originally Posted by vishal.indomitable (Post 432513)
Periodicity means that the thing or part is repeating itself.
Eg: You can take single blade of a turbine runner and apply periodicity.

Symmetry type boundary condition is applied if the geometry is exactly same about a plane. Ex: If you cut any body into exact half and place that body in front of a mirror, you are able to visualise the complete picture of the body.
Vishal, both geometry and flow should be symmetric for symmetric boundary condition to be fully valid. :)


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