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

[mesh manipulation] Problem in SplitMeshRegion when the stl mesh is scaled down

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 27, 2022, 01:54
Default Problem in SplitMeshRegion when the stl mesh is scaled down
  #1
Member
 
Sunag R A
Join Date: Jul 2019
Location: Bangalore, India
Posts: 82
Rep Power: 6
sunagra27 is on a distinguished road
Dear all,


1. Initially, I have assigned stl mesh inside topoSet using surfaceToCell and ran the topoSet. Its working as expected.

2. Afterwards, I run the splitMeshRegion and it gave me correct region splitting with 2 regions(expected).


3. Now, I scaled down the stl mesh to 40%. Again I ran the topoSet with this new stl mesh. The topoSet ran properly.


4. But, when I run splitMeshRegions, it creates many external domain which is not needed. What would be the issue with respect to this?


I have checked the stl mesh using SurfaceCheck before and after scaling it. In both cases, the surface is closed.


Any leads will be appreciated.



Regards,
Sunag R A.
sunagra27 is offline   Reply With Quote

Old   January 28, 2022, 02:33
Default
  #2
Senior Member
 
Gerhard Holzinger
Join Date: Feb 2012
Location: Austria
Posts: 339
Rep Power: 28
GerhardHolzinger will become famous soon enoughGerhardHolzinger will become famous soon enough
Could it be that scaling the STL adversely changes its position relative to the mesh? You can check this easily, by visualising the unscaled and the scaled STL in ParaView.

Scaling the STL may also alter its position in space as is depicted in the attached sketch. On the left, we see an unscaled triangle mesh. If we scale the triangle mesh down, we essentially scale down the position vectors of all triangle nodes. Thus, if the STL is not centered around the coordinate axes, scaling the mesh inevitably changes the position. On the right, we see a scaled triangle mesh, that has been scaled down.
Attached Images
File Type: png scalingSTLerror.png (7.1 KB, 5 views)
GerhardHolzinger is offline   Reply With Quote

Old   January 29, 2022, 00:50
Default
  #3
Member
 
Sunag R A
Join Date: Jul 2019
Location: Bangalore, India
Posts: 82
Rep Power: 6
sunagra27 is on a distinguished road
Quote:
Originally Posted by GerhardHolzinger View Post
Could it be that scaling the STL adversely changes its position relative to the mesh? You can check this easily, by visualising the unscaled and the scaled STL in ParaView.

Scaling the STL may also alter its position in space as is depicted in the attached sketch. On the left, we see an unscaled triangle mesh. If we scale the triangle mesh down, we essentially scale down the position vectors of all triangle nodes. Thus, if the STL is not centered around the coordinate axes, scaling the mesh inevitably changes the position. On the right, we see a scaled triangle mesh, that has been scaled down.

Dear Gerhard Holzinger,


Thank you very much for your reply. I tried to scale down the mesh by keeping the STL centered. The mesh looks good but not splitting into the expected regions as described in the question. As you said scaling may alter the position, how to make it better? Or, is scaling all the time creates this error?


Regards,
Sunag R A.
sunagra27 is offline   Reply With Quote

Reply

Tags
splitmeshregions, stl, toposet


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
[snappyHexMesh] snappyHexMesh stuck when snap is turned on yukuns OpenFOAM Meshing & Mesh Conversion 3 February 2, 2021 13:05
how to set periodic boundary conditions Ganesh FLUENT 15 November 18, 2020 06:09
[ICEM] Problem with using the Delaunay volume mesh method manahara ANSYS Meshing & Geometry 12 December 25, 2014 21:54
[snappyHexMesh] snappyHexMesh won't work - zeros everywhere! sc298 OpenFOAM Meshing & Mesh Conversion 2 March 27, 2011 21:11
unstructured vs. structured grids Frank Muldoon Main CFD Forum 1 January 5, 1999 10:09


All times are GMT -4. The time now is 04:49.