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

[ICEM] Negative Volumes & 7 node HEXA elements

Register Blogs Community New Posts Updated Threads Search

Like Tree1Likes
  • 1 Post By PSYMN

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 16, 2010, 10:34
Default Negative Volumes & 7 node HEXA elements
  #1
New Member
 
Tim Hannah
Join Date: Jun 2010
Posts: 7
Rep Power: 16
mr_stoked is on a distinguished road
Hey guys,

I thought I had finally figured out my turbine blade blocking, my pre-mesh looked good.

I went ahead and tried to export my mesh to Fluent V6 and got this error: "Error : Fluent format does not support 7 node HEXA elements."

My understanding is that this is caused by degenerate elements or elements with negative volume?

I did a pre-mesh quality check on Volume and it said I had some 800,000 elements with negative volume, I clicked on the histogram to check which elements where causing the difficulties and for some reason it displays all of these elements which are outside of my geometry??

I attached some pictures to hopefully give a clearer understanding of my problem.

I would really appreciate any help, this is a thesis project with not long to the deadline.

Thanks.
Attached Images
File Type: jpg negative volumes.jpg (89.0 KB, 68 views)
File Type: jpg blocking.jpg (43.4 KB, 57 views)
mr_stoked is offline   Reply With Quote

Old   September 21, 2010, 13:45
Default Vorfn and 2 Pyramids.
  #2
Senior Member
 
PSYMN's Avatar
 
Simon Pereira
Join Date: Mar 2009
Location: Ann Arbor, MI
Posts: 2,663
Blog Entries: 1
Rep Power: 47
PSYMN has a spectacular aura aboutPSYMN has a spectacular aura about
Perhaps you had the VORFN material active when you created/output your mesh? Make sure it is not active (turn off the part in the model tree) and try again. ICEM CFD maintains these outer blocks in order to maintain index connectivity, etc. But you don't want them active during the conversion from premesh or output to solver. If you do, ICEM CFD will think they are another volume material and will output them.

For those of you with 7 noded elements inside your volume of interest, we added an option at 12.1 (under settings => Hexa Mixed) that will automatically convert these into two pyramids so that your solver won't mind it.
cesarcg likes this.
PSYMN 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
[blockMesh] BlockMesh FOAM warning gaottino OpenFOAM Meshing & Mesh Conversion 7 July 19, 2010 15:11
[blockMesh] Axisymmetrical mesh Rasmus Gjesing (Gjesing) OpenFOAM Meshing & Mesh Conversion 10 April 2, 2007 15:00
negative grid volumes when adapting Dave FLUENT 1 August 20, 2005 14:47
Problem in identifying Negative volumes in Fluent Senthil FLUENT 1 April 19, 2003 11:16
CFX4.3 -build analysis form Chie Min CFX 5 July 13, 2001 00:19


All times are GMT -4. The time now is 00:05.