CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Warning from checkMesh is this serious

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 8, 2008, 10:40
Default Hi, When I issued checkMesh
  #1
Senior Member
 
Pei-Ying Hsieh
Join Date: Mar 2009
Posts: 317
Rep Power: 9
hsieh is on a distinguished road
Hi,

When I issued checkMesh to check my mesh, I got:

***Faces not in upper triangular order
<<Writing 1 unordered faces to set upperTriangularFace
Topological cell zipup check ok
..
Failed 1 mesh check.
--------------------------
Can anyone explain what this means? Thanks!

Pei
hsieh is offline   Reply With Quote

Old   January 8, 2008, 10:55
Default The order of the faces is only
  #2
Senior Member
 
Frank Bos
Join Date: Mar 2009
Location: The Netherlands
Posts: 338
Rep Power: 9
lr103476 is on a distinguished road
The order of the faces is only important for convergence rate of the linear solver. Use renumberMesh to reorder the faces and this message will be gone....

Frank
__________________
Frank Bos
lr103476 is offline   Reply With Quote

Old   January 8, 2008, 11:35
Default Hi, Frank, Thanks for the q
  #3
Senior Member
 
Pei-Ying Hsieh
Join Date: Mar 2009
Posts: 317
Rep Power: 9
hsieh is on a distinguished road
Hi, Frank,

Thanks for the quick respond!

According to the warning message, there is only 1 face that is unordered. When I issued "renumberMesh . case", and then checkMesh, I still got the same warning. Did I use the renumberMesh util correctly?

Pei
hsieh is offline   Reply With Quote

Old   January 8, 2008, 11:49
Default Mmm, that's the way to use it,
  #4
Senior Member
 
Frank Bos
Join Date: Mar 2009
Location: The Netherlands
Posts: 338
Rep Power: 9
lr103476 is on a distinguished road
Mmm, that's the way to use it, works fine here....
__________________
Frank Bos
lr103476 is offline   Reply With Quote

Old   January 8, 2008, 11:50
Default I had the same problem. As fa
  #5
Senior Member
 
Francesco Del Citto
Join Date: Mar 2009
Location: Zürich Area, Switzerland
Posts: 215
Rep Power: 9
fra76 is on a distinguished road
I had the same problem.
As far as I know, that warning is just a small bug in the current checkMesh (1.4.1).
Using renumberMesh, however, can imporve your simulation time a lot!

Francesco
fra76 is offline   Reply With Quote

Old   January 8, 2008, 12:15
Default There's no bug: mesh face orde
  #6
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,762
Rep Power: 21
hjasak will become famous soon enough
There's no bug: mesh face ordering is strictly enforced and necessary for good performance of Incomplete Cholesky preconditioning. Just run renumberMesh and it will get fixed.

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   January 8, 2008, 12:25
Default Hi Hrvoje, that's what I mean
  #7
Senior Member
 
Francesco Del Citto
Join Date: Mar 2009
Location: Zürich Area, Switzerland
Posts: 215
Rep Power: 9
fra76 is on a distinguished road
Hi Hrvoje,
that's what I mean. Even after renumberMesh, the error from checkMesh doesn't disappear. The same happened to Pei.

Francesco
fra76 is offline   Reply With Quote

Old   January 8, 2008, 13:05
Default OK, look at it here: sit in a
  #8
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,762
Rep Power: 21
hjasak will become famous soon enough
OK, look at it here: sit in a cell, visit all neighbours, ask for a cell neighbour label and pick out the smallest one. No error here:

// Add the faces in the increasing order of neighbours
for (label neiSearch = 0; neiSearch < nNeighbours; neiSearch++)
{
// Find the lowest neighbour which is still valid
label nextNei = -1;
label minNei = oldCells.size();

forAll (neiCells, ncI)
{
if (neiCells[ncI] > -1 && neiCells[ncI] < minNei)
{
nextNei = ncI;
minNei = neiCells[ncI];
}
}

if (nextNei > -1)
{
// Face is internal and gets reordered
reverseFaceOrder[curFaces[nextNei]] = nMarkedFaces;

// Stop the neighbour from being used again
neiCells[nextNei] = -1;

nMarkedFaces++;
}
else
{
FatalErrorIn
(
"fvMesh* fvMeshBandCompression::renumberedMesh() const"
) << "Error in internal face insertion"
<< abort(FatalError);
}
}


I bet you've got 2 cells sharing more than one face - that is not allowed.

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   January 22, 2008, 23:12
Default Gents, There are a few ways
  #9
Member
 
David P. Schmidt
Join Date: Mar 2009
Posts: 70
Rep Power: 8
schmidt_d is on a distinguished road
Gents,

There are a few ways I could imagine two cells end up sharing a face. Some of them involve seriously non-convex cells. However, if you just have some degenerate edges, then collapseEdges might be worth a try. You have nothing to lose.

David
schmidt_d 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
CheckMesh error after fluent3DToFoam luca_phi OpenFOAM Mesh Utilities 0 September 17, 2008 03:41
CheckMesh maka OpenFOAM Bugs 2 August 11, 2008 05:13
CheckMesh for mesh quality gdbaldw OpenFOAM Meshing & Mesh Conversion 2 October 18, 2007 00:11
CheckMesh in OF 13 dev 01_05_2007 fra76 OpenFOAM Running, Solving & CFD 5 June 14, 2007 14:16
StarToFoam checkMesh problems sylvain91 OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 1 June 15, 2006 04:36


All times are GMT -4. The time now is 08:47.