Issues with creation of periodic boundaries

Questions and remarks about Code_Saturne usage
Forum rules
Please read the forum usage recommendations before posting.
Post Reply
daniele
Posts: 62
Joined: Wed Feb 01, 2017 11:42 am

Issues with creation of periodic boundaries

Post by daniele » Mon Apr 15, 2019 1:11 pm

Hello,

I would like to create tranlastion periodicity between two parallel boundary faces.
I am using the GUI, v5.0.3.
Looking at the listing, the creation of the periodic "interior" boundary seems successful, since it states:

Code: Select all

Global number of boundary faces selected for joining:      79656

  Element selection successfully done.
  Determination of possible face intersections:

    bounding-box tree layout: 3D

  Global number of intersections detected:       752804
    Vertex-Vertex intersections:          741057
    Other intersections:                   11747

  Joining operation is non-conforming.

  Global number of new vertices to create:      13254

  Equivalences broken for 0 edges.

  Edge intersections and vertex creation done.

  Pre-merge for 48407 global element couples.

  Max size of a merge set of vertices: 6

  Excessive transitivity for 0 set(s) of vertices.

  Edge removed for 0 faces (global).
  Join mesh cleaning done.

  Edge removed for 0 faces (global).
  Join mesh cleaning done.

  Merge vertices and mesh update done.

  Global number of faces after splitting:     122651

  Global configuration after the joining operation:
     Global number of border faces to add:          0

  Mesh cleaning done for degenerate faces.
    Global number of cleaned interior faces:        0
    Global number of cleaned border faces:          0

  After joining
     Number of cells:          358452
     Number of interior faces: 1103329
     Number of boundary faces: 33840
     Number of vertices:       420974


  Joining  1 completed (6.7 s).

  All joining operations successfully finished:

    Wall clock time:                   6.7
Nevertheless, after importing the preprocessor.log, I can still see the two original boundary faces in the boundary regions list. This is not consistent with the Code_Saturne documentation stating that: "Once a periodicity
is handled, faces having periodic matches do not appear as boundary faces, but as interior faces, and
are thus not available anymore for other periodicities".

On the other hand, opening the BOUNDARY_GROUPS.case in Paraview, the two original faces are not visible anymore after extracting blocks. They are available as "interiorjoinedFaces_j01" in the separated JOINING.case.

Is there a way to double check the correct creation of a periodic boundary condition?

Many thanks in advance.

Best regards,

Daniele

Yvan Fournier
Posts: 2678
Joined: Mon Feb 20, 2012 3:25 pm

Re: Issues with creation of periodic boundaries

Post by Yvan Fournier » Mon Apr 15, 2019 11:00 pm

Hello,

The preprocessor only imports the mesh (or meshes) and possibly checks for orientation, so its log is relevant only for these initial stages. The actual joining is done by the solver part (it was done in the preprocessor a long time ago).

So the information you need to check (between boundary and interior faces) is in the listing, not in the preprocessor.log.

Judging by what you observe (both "interiorjoinedfaces" and no presence in the boundary mehs), things seem to be good.

Best regards,

Yvan

daniele
Posts: 62
Joined: Wed Feb 01, 2017 11:42 am

Re: Issues with creation of periodic boundaries

Post by daniele » Thu May 02, 2019 9:59 am

Hello Yvan,

Thank you very much for your reply.
I am still struggling with correctly creating the periodicity.
Actually everything seems to be ok, but looking at the results the periodic boundary behaves as a wall (zero cross velocity).
One question: I guess I need to manually remove the periodic boundaries from the boundaries list, after reading the preprocessor.log. Do you confirm this?

Thanks a lot in advance.

Best regards,

Daniele

Yvan Fournier
Posts: 2678
Joined: Mon Feb 20, 2012 3:25 pm

Re: Issues with creation of periodic boundaries

Post by Yvan Fournier » Thu May 02, 2019 5:00 pm

Hello,

No, as I explained, periodicity is built by the solver, so you need to check the "listing" (or run_solver.log under v6.0), for boundary zones, not the preprocessor.log.

You should not need to do anything manually, but if the mesh joining is incomplete, you might still have some faces behaving as a wall. You can check this with the joining visualization.

Also,do you have an inlet to "force" the flow, or are you using a velocity source term ?

Regards,

Yvan

Post Reply