[pankos]

Is there any way to make periodic mesh in gambit? With other words, the elements on a side to connect with elements of other side as there is continuity. Therefore in NEUTRAL file (which export the mesh) to not put boundary on this side but only nodes and connectivity.

[-mAx-]

from Help:
*******
NOTE: To apply a "periodic" boundary condition for use with a FLUENT solver, you must first create a mesh hard link between the pair of edges (2-D) or faces (3-D) to which the boundary condition is to apply. In addition, you must assign a PERIODIC boundary type to both edges (or faces) in the pair, and both edges (or faces) must constitute members of a single entity set.

[pankos]

No, i dont use FLUENT, but code which i made it. Due to i can take mesh information only by ASCII neutral file (Generic).
If i select Generic at solver menou , it doesnt appear any periodic boundary at Boundaries.

For example, on two opposite sides of rectangular to there are the same nodes (number node) so that to appear that there is continuity.

[-mAx-]

Then I don't know but I would respect the hard link between your periodic surfaces: each periodic surface shouldhave exactly same mesh.
Define them as separated BC and assign as element size.
After that you will be able to pick those surfaces and apply BC with your code

[pankos]

Ok. As shown, the only way is this. It must be construct only by code.

But, if in connectivity list of elements which derived by Mesh generator, has same number (indexing )of nodes at two face then two faces will be periodic. Of course, here, there is a problem. The two faces are dif topologies,therefore it can not be have same coordinates of nodes.

Thanks.

[-mAx-]

if your surfaces don't have same topology, are they still periodic?

[pankos]

yes. The continuity of a side is other side. i dant know, i wiil try to make this in my code but of course without any generallity.

[PSYMN]

Is you problem generating a mesh with corresponding periodic nodes? Or is the problem that Fluent just doesn't give you the opportunity to apply a periodic boco (the Periodic Conditions button is not available)?

If it is the latter, make sure that each side has its own separate boundary condition name (like Per1 and Per2). Then, via the command prompt (type

define/ boundary-conditions/ modify-zones/ make-periodic>

This causes Per1 and Per2 to merge into a single periodic boundary condition and the "Periodic Conditions" button becomes available for further settings.

[pankos]

All periodic conditions are problems of solver and not Mesh generator. Simply, the mesh generator determine the edges which have Periodic B.C.
If was problem of mesh generator must be put tha same nodes (index of node) at the periodic edges so that appear as continuity. Of course, the coordinates of these nodes is not determined clearly because belong to different edges. Therefore, as output file must be export the connectivity list (doing the consideration that the nodes of Edges of P.B.C are same) and for coordinates of nodes (doing consideration that these nodes are different).