CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Periodic Boundary Conditions

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree2Likes
  • 1 Post By flotus1
  • 1 Post By Persil

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 4, 2013, 06:12
Default Periodic Boundary Conditions
  #1
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
Hello,

there are quite a few threads to this topic here, but I tried multiple methods already so starting a new 1 sems legit...

as you can see in the picture, I want to create to periodic boundary conditions: a) the faces on the top, b) the faces on the bottom

creating works without an error, but when exporting the mesh, following error appears:

"boundary entity ***_shadow does not contain any valid entity and is not written.
periodic boundary entity *** is not specified correctly. The two periodic entities must be link meshed and specified on the same boundary entity."

the problem is: I thought I did that already by face-linking the top and bottom before starting, splitting edges/faces and creating stuff... I even renewed the mesh-link when I splitted the volume and merged faces afterwards, because there I got the message, that mesh-links had been deleted to compute the command

I also tried keeping the bc as SYMMETRY and then changing them later in fluent to PERIODIC, but this was also not possible...

Nex thing I want to do is exporting with bc INTERFACE and then create periodic bc in fluent, but dont know if this is sufficient...

any ideas?
Attached Images
File Type: jpg Vane_periodic.JPG (42.5 KB, 56 views)
Persil is offline   Reply With Quote

Old   December 4, 2013, 06:37
Default
  #2
Super Moderator
 
flotus1's Avatar
 
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,384
Rep Power: 46
flotus1 has a spectacular aura aboutflotus1 has a spectacular aura about
Quote:
Originally Posted by Persil View Post
I also tried keeping the bc as SYMMETRY and then changing them later in fluent to PERIODIC, but this was also not possible...

Nex thing I want to do is exporting with bc INTERFACE and then create periodic bc in fluent, but dont know if this is sufficient...
(
"was also not possible" is a bit unspecific as an error description, but I guess that you did not find anything called "periodic" in the drop-down list.

Generally, you have two options to create periodic boundary conditions in Fluent directly. For both of them, the name or initial type of the boundaries involved are irrelevant.
  1. non-conformal interface via GUI
    Set the types of the two boundaries to interface. Then you can create a periodic interface in the mesh interfaces tab in Fluent.
  2. periodic boundary condition via TUI
    Enter "mesh" "modify-zones" make-periodic"
    Here you will have to specify the IDs of the boundaries involved (find them in the boundary conditions tab) and if you want a rotational or a translational periodicity.
    For this method, the meshes on both surfaces must be conformal.
Mohammad74 likes this.
flotus1 is offline   Reply With Quote

Old   December 4, 2013, 07:28
Default
  #3
Member
 
vidyanand
Join Date: Nov 2011
Location: bangalore,india
Posts: 66
Rep Power: 17
Vidyanand Kesti is on a distinguished road
the mesh size at the both side is same?

is it rotating periodic then it should be an angle with origin
Attached Images
File Type: png Untitled.png (11.3 KB, 30 views)
Vidyanand Kesti is offline   Reply With Quote

Old   December 4, 2013, 08:51
Default
  #4
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
thx for the quick replies!

yes, I was not able to choose periodic from the drop down list...

@flotus1: Those are the 2 methods I tried and failed, because I forgot to apply them as rotating periodicity...

Now I used /grid/modify-zones/mp with checking yes as rotating

... and fluent was able to create a periodic bc out of the two interface-zones, 1 was deleted in the process and now I can get information about the new zone via right-clicking, but when I right-click on the shadow-zone the attachment is displayed. Do I have to check the grid again or how will the zones be renumbered without giving an error?

--> saving the file solves that problem
Attached Images
File Type: jpg Periodic_zone_display.JPG (53.5 KB, 30 views)
Persil is offline   Reply With Quote

Old   December 4, 2013, 11:00
Default
  #5
Senior Member
 
RodriguezFatz's Avatar
 
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 26
RodriguezFatz will become famous soon enough
Where do you right-click? In the 3d window on the mesh?
__________________
The skeleton ran out of shampoo in the shower.
RodriguezFatz is offline   Reply With Quote

Old   December 4, 2013, 11:06
Default
  #6
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
yes, I right-clicked in the 3D-window which displays the mesh and there on the zone, which I labeled to be the shadow-zone when I created the periodic bc... then the error was displayed, but this could be solved by just saving the file and open it again
Persil is offline   Reply With Quote

Old   December 4, 2013, 11:07
Default
  #7
Senior Member
 
RodriguezFatz's Avatar
 
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 26
RodriguezFatz will become famous soon enough
Alright, because in my file I can't click on the shadow zone...
__________________
The skeleton ran out of shampoo in the shower.
RodriguezFatz is offline   Reply With Quote

Old   December 4, 2013, 11:37
Default new question
  #8
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
yes, when I open the file again after saving, I cannot select the shadow zone, it will always be labeld as the periodic zone...

I got another question, that kind of follows up: I imported several mesh files into gambit. When I export them as 1 mesh, which will then be imported into fluent, changing the boundary condition to periodic via mesh>modify>mp is no problem...
but if create groups in gambit, arrange them via "align" and import the mesh file into fluent, not all boundary conditions can be changed to periodic... how does the group alignment disable the change of boundary conditions?
Persil is offline   Reply With Quote

Old   December 10, 2013, 09:05
Default periodic boundary condition
  #9
New Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 12
ascedragon is on a distinguished road
i also have problems about periodic boundary condition.. i already have a design of two steam turbine blade. can someone please help me step by step from mesh part to fluent so that i get the periodic boundary condition..... help me turbo engineer...
ascedragon is offline   Reply With Quote

Old   December 10, 2013, 09:19
Default
  #10
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
before meshing or even spliting edges and faces, you have to face-link the periodic boundaries, so that everything you do at one border will be mirrored onto the other...

but still in Gambit for me it was not possible to export periodic boundayries, I asigned them as SYMMETRY and changed them later in fluent via mesh/modify/mp to PERIDIC boundaries
ascedragon likes this.
Persil is offline   Reply With Quote

Old   December 10, 2013, 09:28
Default
  #11
New Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 12
ascedragon is on a distinguished road
thanks persil for helping me.. how can i face-link the periodic boundaries? i dont know to choose which one is the high and low boundary in my design.. i'm still amateur using CFD software..
ascedragon is offline   Reply With Quote

Old   December 10, 2013, 10:47
Default
  #12
Member
 
Join Date: Nov 2013
Posts: 43
Rep Power: 12
Persil is on a distinguished road
I am new to cfd also, so I can only help you with things I experienced in the last weeks and well thought guesses

I don't think that it matters which 1 you choose as the top 1, as long as the vertices you select are corresponding to the surfaces

Do you use gambit for the meshing? there you face-link via face and vertex selection, where you can enable periodic and reverse (if needed)
Persil is offline   Reply With Quote

Old   December 10, 2013, 12:38
Default
  #13
New Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 12
ascedragon is on a distinguished road
no, i'm using ansys workbench 14.5..
ok, thanks persil.. i will try...
ascedragon is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
ribbed channel / simpleFoam / boundary conditions beeo OpenFOAM Pre-Processing 20 July 17, 2013 09:39
Error finding variable "THERMX" sunilpatil CFX 8 April 26, 2013 08:00
periodic boundary conditions fro pressure Salem Main CFD Forum 21 April 10, 2013 01:44
Periodic boundary conditions in 3D Eulerian granular flow simulations dsm FLUENT 4 March 2, 2012 20:04
periodic boundary conditions mranji1 Main CFD Forum 4 August 25, 2009 00:45


All times are GMT -4. The time now is 16:12.