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Puneet July 11, 2003 16:37

Specifying Periodic Boundary
I am importing a readymade plot3d formatted turbine rotor grid in gambit. However for specifying the periodic boundary conditions when I try to periodically link the two faces together, A major part of my volume grid gets eaten away. Is there a way out of this?

gelislim July 17, 2003 08:54

Re: Specifying Periodic Boundary
Hi Puneet,

The reason is that gambit regenerates one of the face meshes to assure that they are conformal. Try to link faces before meshing the volume.

Good Luck

Puneet July 17, 2003 11:50

Re: Specifying Periodic Boundary
Well How do I make the faces conformal and apply the periodic BCs if I have a grid that has been provided to me rather than I generating it in gambit. Any solutions.

gelislim July 18, 2003 06:16

Re: Specifying Periodic Boundary
In this case the only solution is to use non-conformal periodicity capability of Fluent(6.0 and later versions). Steps are:

1) Define each faces that will be periodic using different names(lets say wall-1 and wall-2) in gambit and write the mesh file

2) Read the mesh file into fluent. After issuing standarts commands (grid check, grid scale etc...) use define-boundary conditions menu to change the fluid properties(if the periodicity is rotational). Define rotation axis,direction and speed of fluid.

3) Change the type of wall-1 and wall-2 to interface

4) Use text user interface(TUI) to reach /define/grid-interfaces menu. Issue make-perodic command.Here,you need to specify the face id numbers, periodicity angle and name of periodic boundary to be created.

5) Finally, check your grid again and be sure that Fluent gives correct periodicity angles on TUI

6) Define other bc`s, make solver set up and start iteration.

Good luck

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