CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > STAR-CCM+

zero-area faces, urgent!

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 7, 2009, 05:07
Default zero-area faces, urgent!
  #1
Member
 
Radiatn
Join Date: Mar 2009
Posts: 34
Rep Power: 8
radiatn is on a distinguished road
hi!
what to do if we see this message:

Updating interface In-place 2 between Region 1:HX rad core and Region 5 Rad intface:rad core tolerance 0.02
Created 115262 intersection faces (100% of master area, 99% of slave area)
Info: mesh in Physics 1 fluid contains 32 zero-area faces.
Calculating grid flux in region Volume Mesh:Region 4 Cond intface

Shortly after, my run will stop, without passing a single iteration. It could be due to this zero-area faces but i dont know how to get rid of it. Any help would be appreciated!
radiatn is offline   Reply With Quote

Old   June 7, 2009, 10:28
Default
  #2
Senior Member
 
Join Date: Mar 2009
Location: Austin, TX
Posts: 134
Rep Power: 9
kyle is on a distinguished road
It is unlikely that the zero area faces are causing divergence. You have something else going on.

You can try doing remove invaldid cells with some agressive settings. Do it AFTER you initialize the solution.
kyle is offline   Reply With Quote

Old   June 7, 2009, 20:09
Default
  #3
Member
 
Radiatn
Join Date: Mar 2009
Posts: 34
Rep Power: 8
radiatn is on a distinguished road
Hi Kyle,

Thanks, I've done that with 10 different settings but still getting divergence error. In the manual it says no problem if single precision but i dont know if by default ccm is set using single or double precision? Do you know how to change to single precision in ccm? (can't find it in the manual).

the error says (wish i could attach picture in this website):

server error: a floating point exception has occurred: floating point exception [divide by zero]. the specific cause cannot be identified. potential cause may include: (a) solution divergence due to poor mesh quality, crude initialization, etc., or (b) errors in user-define code or field functions.

Above is copied verbatim. I dont use user-coding and the mesh is trimmed cells (tried with slow, medium and fast growth rate) with porous and rotating regions. I've tried deleting those porous and rotating regions altogether but same error appeared. Changed the physics to very basic until it makes no physical sense (inviscid and laminar) and still getting same error. Frozen all solvers except segregated flow and that could run it to 1 iteration but at 2 iteration got same eror. Yesterday, i auto-repair the remeshed surface and i got zero errors after auto-repair. The tech support also could not help me much so if anyone has encountered the same problem, please point me to right direction. Been working 4 weekdays and all weekend on this. It's due today.
radiatn is offline   Reply With Quote

Old   June 8, 2009, 04:24
Default
  #4
SKK
Member
 
Join Date: Mar 2009
Posts: 55
Rep Power: 8
SKK is on a distinguished road
I have had similar problems a few times. In most of these cases, the only way was to recreate the mesh!!! This was because nothing I did got rid of this error. As a result I got into the habit of saving different stages of the meshing process, so i can always go back to the previous stage if that happens and not have to generate the mesh from the very start. But in some cases I think it is definitely due to bad qulaity cells. I assume you have interfaces. How are you getting rid of the bad cells?

The method I use is to use split by function to remove negative volume cells. After this initiate the solutions. You should get the same error message at this stage. Now you can either delete the solution and decrease the interface tolerance before reinitiatiing or, if the number of bad cells are not many then simply remove these by right clicking on the regions and selecting 'remove invalid cells' WITHOUT removing the solution. The reinitiate the solution. If even after this you get the same error, than unfortunately there is nothing much you can do. But do get in touch with support guyes.
SKK 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
DecomposePar unequal number of shared faces maka OpenFOAM Pre-Processing 6 August 12, 2010 09:01
BlockMeshmergePatchPairs hjasak OpenFOAM Native Meshers: blockMesh 11 August 15, 2008 07:36
Unaligned accesses on IA64 andre OpenFOAM 5 June 23, 2008 10:37
CFX Solver Memory Error mike CFX 1 March 19, 2008 08:22
Zero area faces on the axis as symmetryPlane make OpenFOAM Running, Solving & CFD 2 October 16, 2007 05:47


All times are GMT -4. The time now is 10:30.