[Amoul]

Hello,
I would like to know the difference between periodic and symmetry boundary conditions?
Thanks,

[vishal.indomitable]

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]

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]

Originally Posted by vishal.indomitable

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.