CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Pre-Processing

Defining boundary conditions STL file

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 19, 2012, 08:15
Default Defining boundary conditions STL file
  #1
New Member
 
Join Date: Apr 2012
Posts: 5
Rep Power: 5
marco100 is on a distinguished road
Hi,

Since I just started exploring OpenFOAM I have a basic question.
I want to make a simulation of the air distribution in a building. I have the geometry available in an STL file (the building is drawn with AutoCAD). The STL file consists of one single block (containing the building, i.e. the walls, floor and ceiling). Inside it is open and this is the space where of course the air distribution has to be calculated.
So in the STL file there isn't any boundary condition prescribed yet (for instance there isn't an opening in a wall where air from outside can come in, the opening is something I have to create).
How can I define such an opening and get the geometry running in OpenFOAM? I have been playing with Salome and Engrid but it is not clear to me. It seems I cannot make any changes to the STL geometry.
I hope my question is clear.

Best regards,
Marco
marco100 is offline   Reply With Quote

Old   April 19, 2012, 08:33
Default
  #2
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 463
Rep Power: 9
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
I would usually separate some of the triangles of your stl to a different stl file, give the latter a different name and use it to set a boundary condition on it.
lovecraft22 is offline   Reply With Quote

Old   April 19, 2012, 08:40
Default
  #3
New Member
 
Join Date: Apr 2012
Posts: 5
Rep Power: 5
marco100 is on a distinguished road
Thanks for your reply.
So Openfoam can read in multiple STL files?
What would be the best pre-processor to make the separation? It seems some triangles are really big, maybe bigger than the opening I want to create. Do you have an idea for this?
marco100 is offline   Reply With Quote

Old   April 19, 2012, 08:43
Default
  #4
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 463
Rep Power: 9
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Yes, it can read multiple stl or even a stl with multiple regions in it.

About your problem, there are specific softwares that can do what you ask, but probably in your case the easiest way would be that of using a cad, cut the hole and save the file as building.stl, then generate a surface to cover your hole and save it as inlet.stl (or whatever you'd like). Any cad can do that.
lovecraft22 is offline   Reply With Quote

Old   April 19, 2012, 09:01
Default
  #5
New Member
 
Join Date: Apr 2012
Posts: 5
Rep Power: 5
marco100 is on a distinguished road
I dont have a lot of experience with CAD programs. I only have the STL file. Can I read that in into a CAD program and make the changes you suggest?
marco100 is offline   Reply With Quote

Old   April 19, 2012, 09:06
Default
  #6
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 463
Rep Power: 9
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Yes, any cad software can do that.
lovecraft22 is offline   Reply With Quote

Old   April 19, 2012, 09:28
Default
  #7
New Member
 
Join Date: Apr 2012
Posts: 5
Rep Power: 5
marco100 is on a distinguished road
I have AutoCAD but it cannot open STL files, only export it in that format.
marco100 is offline   Reply With Quote

Old   May 23, 2012, 08:06
Default
  #8
Senior Member
 
Elvis
Join Date: Mar 2009
Location: Sindelfingen, Germany
Posts: 577
Blog Entries: 5
Rep Power: 13
elvis is on a distinguished road
Hi,

you might take a look at Blender
For an older Blender versions there are even OpenFoam related Tutorials
http://openfoamwiki.net/index.php/Tut_andrew_blender
nice thread here
Blender export script for named ASCII STLbs

http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro for different Blender tasks
elvis 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
Wind turbine simulation Saturn CFX 34 October 16, 2014 05:27
wmake compiling new solver mksca OpenFOAM Programming & Development 13 August 18, 2014 22:26
error message with modeling a cube with a hold at the center hsingtzu OpenFOAM Native Meshers: blockMesh 2 March 14, 2012 10:56
Version 15 on Mac OS X gschaider OpenFOAM Installation 120 December 2, 2009 11:23
OpenFOAM on MinGW crosscompiler hosted on Linux allenzhao OpenFOAM Installation 127 January 30, 2009 20:08


All times are GMT -4. The time now is 09:05.