CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Bugs

snappyHexMesh is generating cells with flat faces touching each other

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

LinkBack Thread Tools Display Modes
Old   January 19, 2015, 04:55
Exclamation snappyHexMesh is generating cells with flat faces touching each other
Senior Member
Join Date: Oct 2013
Posts: 380
Rep Power: 7
chriss85 is on a distinguished road
I've recently run into problems where snappyHexMesh will generate polyhedra cells with a nonzero volume, but two faces directly on top of each other.

This results in problems because the Courant number will be extremely high in these cells, and adaptive time step methods will fail.

This problem is not detected by checkMesh, since common quality measures like non-orthogonality or cell volume are unaffected. I think this issue needs to be considered in the detection of invalid cells during undo stage in snappyHexMesh.

For reference, here's the checkMesh output:
    Overall domain bounding box (-2.10476e-08 1.47089e-05 1.07802e-05) (0.017315 0.0186159 0.0183828)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (-8.91807e-17 -2.58947e-17 -6.77004e-18) OK.
    Max cell openness = 3.89026e-16 OK.
    Max aspect ratio = 5.73767 OK.
    Minimum face area = 4.2135e-10. Maximum face area = 4.23884e-08.  Face area magnitudes OK.
    Min volume = 4.94644e-14. Max volume = 7.47925e-12.  Total volume = 3.39481e-07.  Cell volumes OK.
    Mesh non-orthogonality Max: 55.4823 average: 10.0927
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 1.68602 OK.
    Coupled point location match (average 0) OK.
If any further information is required, feel free to ask me.
Attached Images
File Type: png weirdCell.png (4.2 KB, 15 views)
File Type: png weirdCell1.png (4.8 KB, 13 views)

Last edited by chriss85; January 19, 2015 at 10:39.
chriss85 is offline   Reply With Quote


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
Cluster ID's not contiguous in compute-nodes domain. ??? Shogan FLUENT 1 May 28, 2014 15:03
createPatch Segmentation Fault (CORE DUMPED) sam.ho OpenFOAM Pre-Processing 2 April 21, 2014 02:01
Doxygen documentation Tanay OpenFOAM Installation 9 September 23, 2011 11:40
Import netgen mesh to OpenFOAM hsieh Open Source Meshers: Gmsh, Netgen, CGNS, ... 32 September 13, 2011 05:50
Unaligned accesses on IA64 andre OpenFOAM 5 June 23, 2008 10:37

All times are GMT -4. The time now is 11:19.