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

SnappyHexMesh

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 29, 2012, 00:51
Default SnappyHexMesh
  #1
New Member
 
Anone
Join Date: Feb 2012
Posts: 16
Rep Power: 14
CFD_user_2012 is on a distinguished road
Hi all

I created a stl file of a square cylinder to test the snappyHexMesh function. I created my domian first using the blockMesh. That was OK. Then I placed my stl file in the trisurfacemesh folder. Then I ran snappy hexMesh

The messages indicate that there is no error, but when I open using paraFoam all I get is a square cylinder meshed without the domain.



What is wrong ?


CFD_user
CFD_user_2012 is offline   Reply With Quote

Old   February 29, 2012, 04:04
Default
  #2
Senior Member
 
romant's Avatar
 
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20
romant is on a distinguished road
Is your point from which you start meshing inside the cylinder? is your blockmesh at the right position of the stl surface? you can check that by opening your stl surface while you have your blockmesh open in parafoam.
__________________
~roman
romant is offline   Reply With Quote

Old   February 29, 2012, 05:04
Default
  #3
Member
 
Join Date: Nov 2009
Location: Germany
Posts: 96
Rep Power: 16
val46 is on a distinguished road
Did you use sHM with the "-overwrite" option? If not, you get 2 more timestep folders 1 and 2. In there you will find your castellated and your snapped mesh. (choose the timesteps in paraview)
__________________
"When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first." Werner Heisenberg
val46 is offline   Reply With Quote

Old   February 29, 2012, 16:59
Default snappyHex mesh
  #4
New Member
 
Anone
Join Date: Feb 2012
Posts: 16
Rep Power: 14
CFD_user_2012 is on a distinguished road
Hi

I generated my blockmesh and then I opened it using parafoam. Then I opened the stl file and then checked the position and orientation of the stl object with the domain. Everything is fine. I then use snappyhexmesh.

I looked at the different time folders also.

I find this problem only with simple geometry such as a square cylinder or cube. When I use a complicated stl file downloaded from the internet then it works fine.

CFD_user
CFD_user_2012 is offline   Reply With Quote

Old   February 29, 2012, 17:06
Default Bug
  #5
New Member
 
Anone
Join Date: Feb 2012
Posts: 16
Rep Power: 14
CFD_user_2012 is on a distinguished road
Hi

Is this a possible bug in the software ?


CFD_user
CFD_user_2012 is offline   Reply With Quote

Old   February 29, 2012, 17:52
Default
  #6
Retired Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
Blog Entries: 45
Rep Power: 128
wyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to all
Greetings to all!
Quote:
Originally Posted by CFD_user_2012 View Post
I find this problem only with simple geometry such as a square cylinder or cube.
If it's simple and small, then upload the case before running blockMesh and snappyHexMesh, so we can look at it and tell you if it's just a usage problem or a bug.

Best regards,
Bruno
__________________
wyldckat is offline   Reply With Quote

Old   February 29, 2012, 18:54
Default
  #7
Senior Member
 
sail's Avatar
 
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
Posts: 308
Rep Power: 16
sail is on a distinguished road
have you checked that the point that tells to sHM the inside of the volume domain is palced in a reasonable position and not in your stl? can you post some pictures of the error you are having?
__________________
http://www.leadingedge.it/
Naval architecture and CFD consultancy
sail is offline   Reply With Quote

Old   February 29, 2012, 21:47
Default snappyhexmesh
  #8
New Member
 
Anone
Join Date: Feb 2012
Posts: 16
Rep Power: 14
CFD_user_2012 is on a distinguished road
Hi

OK this is my file. Let me know whats wrong



thanks
CFD_user
Attached Files
File Type: gz test_cylinder.tar.gz (14.2 KB, 17 views)
CFD_user_2012 is offline   Reply With Quote

Old   March 2, 2012, 07:31
Default
  #9
Retired Super Moderator
 
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
Blog Entries: 45
Rep Power: 128
wyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to allwyldckat is a name known to all
Hi CFD_user,

Instead of:
Code:
    refinementBox
    {
        type searchableBox;
        min (-100.0 -0.7 0.0);
        max ( 80.0  0.7 20.5);
    }
Use something like:
Code:
    refinementBox
    {
        type searchableBox;
        min (-100.0 -0.7 0.0);
        max (282  233 256);
    }
I used ParaView's "Menu->Sources->Ruler" to see where these points are. This box now properly covers the cube, to give enough resolution for snapping things later.

Then, instead of:
Code:
    locationInMesh (0.3 30 0.43);
Use:
Code:
    locationInMesh (752.1231 300.3423 300.4234);
I used the "Menu->Sources->Sphere" for seeing where this point was. This point is nowhere near the cube and is in a position where:
Code:
    // NOTE: This point should never be on a face, always inside a cell, even
    // after refinement.
You should learn (as soon as possible!), to pay more attention to the numbers you are using! They can be your friends if you use them right; but if wrongly used, then your worst nightmares can come true

Best regards,
Bruno
Attached Images
File Type: jpg proper_meshing.jpg (71.7 KB, 44 views)
__________________

Last edited by wyldckat; March 3, 2012 at 09:47.
wyldckat is offline   Reply With Quote

Old   March 4, 2012, 22:09
Default SnappyHexMesh
  #10
New Member
 
Anone
Join Date: Feb 2012
Posts: 16
Rep Power: 14
CFD_user_2012 is on a distinguished road
Hi Bruno

Thanks very much, works perfectly.


CFD_user
CFD_user_2012 is offline   Reply With Quote

Old   March 8, 2012, 07:48
Default
  #11
Super Moderator
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Tussenhausen
Posts: 2,708
Blog Entries: 6
Rep Power: 51
Tobi has a spectacular aura aboutTobi has a spectacular aura aboutTobi has a spectacular aura about
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
hi bruno,

thx for your post!
you helped me a few times and your discriptions are very good
I learn everytime something new if i read your posts (here using paraview to see the points)!

THX

Tobi
Tobi is offline   Reply With Quote

Reply


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 Issues deji OpenFOAM Meshing & Mesh Conversion 16 October 20, 2021 07:13
Strange Results With snappyHexMesh calebamiles OpenFOAM Running, Solving & CFD 0 August 14, 2011 16:02
[snappyHexMesh] stitchMesh and snappyHexMesh gdbaldw OpenFOAM Meshing & Mesh Conversion 0 December 23, 2009 02:09
[snappyHexMesh] SnappyHexMesh samiam1000 OpenFOAM Meshing & Mesh Conversion 0 October 5, 2009 10:32
[snappyHexMesh] SnappyHexMesh not generate mesh first time mavimo OpenFOAM Meshing & Mesh Conversion 4 August 26, 2008 07:08


All times are GMT -4. The time now is 22:54.