CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Meshing & Mesh Conversion

Splitting the Boundaries

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

Like Tree3Likes
  • 3 Post By linnemann

Reply
 
LinkBack Thread Tools Display Modes
Old   October 10, 2018, 07:12
Default Splitting the Boundaries
  #1
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
Dear Foamers,
I read threads about toposet and others regarding spliiting patches etc.
But I still struggeling with that.
My goal is to split each of my Boundary-sides.

I have something like a Box with left, right, front, back sides (forget the top and the bottom). I would like to split each of these 4 sides into two (so cutting each by the half) to have more flexible Boundary conditions.
Has anyone an idea how to handle this?
Chris123 is offline   Reply With Quote

Old   October 10, 2018, 08:20
Default
  #2
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
Easiest way to do this is using Paraview.

Follow this guide to select the cells you want in you BC.
Remember to turn off "internalMesh" when you load the case.



After this use surfaceToPatch with the stl you just made.

jherb, Tobi and peterhess like this.
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 10, 2018, 09:21
Default
  #3
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
many many thanks Niels.
But I got an fatal error if i execute surfaceToPatch with:"No Mesh available, Probaply mesh is not read."
Which sounds strange to me because my mesh is of course there!
Do you have any idea where the error comes from?
Chris123 is offline   Reply With Quote

Old   October 10, 2018, 10:51
Default
  #4
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
Could you please list the exact command you ran and the output of checkMesh.

Also an OF version would be nice to know.
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 11, 2018, 09:11
Default
  #5
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
The error comes from the saved surface stl file. In my case it is empty becasue paraview complains that stl files does only support triangles, I have an irregular grid. I tried it with a polygonal file format, but this does not work with the "surfaceToPatch command. The other file formats (e.g vtm)to save the surface extraction which paraview suggested fails as well.
Any idea to overcome this issue?
Chris123 is offline   Reply With Quote

Old   October 11, 2018, 09:12
Default
  #6
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
Could you share the case?
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 12, 2018, 01:57
Default
  #7
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
I have a complicated environment 5terrain case which is very huge. Therefore I tried your method also on the wind around Buildings tutorial, and it fails with the same error message. A bit strange, can you maybe try on that as well?
Chris123 is offline   Reply With Quote

Old   October 12, 2018, 03:27
Default
  #8
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
Are you sure you followed all my steps?

1. Select surface cells to be used for BC
2. Extract selection
3. Extract surface
4. Save Data -> choose stl and ascii output.
5. Try and load the stl and see it is triangulated

I did this for a case made with snappyHexMesh and have no problems.

EDIT:
Just used the windAroundBuildings tutorial and it work fine.
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 12, 2018, 05:43
Default
  #9
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
Yes, I made an animated gif, the same as your guidance but unfortunately I'am not able to share it with you. I cannot attach it as an gif the attachment management convert it to a jpg.
Sorry.
Chris123 is offline   Reply With Quote

Old   October 12, 2018, 06:25
Default
  #10
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
I use imgur and then use the link to the gif here on the forum using "Insert Image".
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 12, 2018, 06:33
Default
  #11
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
Hi Niels, many thanks for your Help, and your excellent guidance.
If I apply a Triangulate filter before saving the surface stl file it works.
Maybe it is somewhere predefined in your setting otherwise I do not know why you denot need it?
Anyway, again many thanks.
Chris123 is offline   Reply With Quote

Old   October 12, 2018, 07:00
Default
  #12
Senior Member
 
linnemann's Avatar
 
Niels Nielsen
Join Date: Mar 2009
Location: NJ - Denmark
Posts: 501
Rep Power: 21
linnemann will become famous soon enough
Maybe it is the Paraview version?
I'm using 5.5 on windows for the one I made.
__________________
Linnemann

PS. I do not do personal support, so please post in the forums.
linnemann is offline   Reply With Quote

Old   October 15, 2018, 04:53
Default
  #13
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
Dear Nils,
sorry to come back again. After I could split each of my 4 patches successfully, the way forward is not clear to me.
I mean now I have 8 new polymesh folders for each new splittet patch in terms of:

oldside A splittet in SideA half1 and half2
oldside B splittet in SideB half1 and half2
oldside C splittet in SideC half1 and half2
oldside D splittet in SideD half1 and half2

Now I think I have to merge all of them and deleted the old entries out to have a new (combined)boundary, face, patch, owner, points and neighbour file inside the polymesh. But how, Or do I miss something?
Chris123 is offline   Reply With Quote

Old   October 16, 2018, 09:21
Default
  #14
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
What I did in the meantime, is that I meshed the new splittet stl files with snappyhexmesh. So I think have what I want, but how I get rid of the old patches, how can I delete these. I read some other threads but I did not find the answer yet.
Any idea?
Chris123 is offline   Reply With Quote

Old   October 17, 2018, 06:27
Default
  #15
New Member
 
Chris Schäfer
Join Date: Apr 2017
Posts: 19
Rep Power: 3
Chris123 is on a distinguished road
Problem solved. Just using in the beginning the "half" names for each patch.
Chris123 is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
2D Rotating Detonation Engine Periodic Boundaries whitet86 FLUENT 2 June 25, 2015 11:04
Flux difference splitting Vs Fluctuation splitting Vino Main CFD Forum 0 January 18, 2014 15:54
Flux splitting Dr B.M. Smith (Smith) OpenFOAM Running, Solving & CFD 19 January 9, 2013 04:07
Setting Flow/Pressure Boundaries in Floworks Eran FloEFD, FloWorks & FloTHERM 3 August 11, 2009 04:23
periodic boundaries - flow through a net PK FLUENT 0 July 12, 2007 11:58


All times are GMT -4. The time now is 17:29.