CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > OpenFOAM

Cell determinant (wellposedness)

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

Like Tree4Likes
  • 1 Post By Zowie
  • 1 Post By anothr_acc
  • 1 Post By Ship Designer
  • 1 Post By ghastbug

LinkBack Thread Tools Search this Thread Display Modes
Old   September 27, 2010, 14:04
Default Cell determinant (wellposedness)
New Member
Join Date: Jun 2009
Location: Murcia, Spain
Posts: 14
Rep Power: 15
Zowie is on a distinguished road
I'm pretty sure there isn't a single thread in the forum dealing with this thema and I hope that somebody can shed some light on this.

checkMesh says my mesh is OK, but if I run "checkMesh -allGeometry -allTopology" I get a huge number of cells with small determinant that are written to a faceSet undeterminedCells.

I guess I need to change my numerical schemes, but in order to do that I need to understand how this small determinant values affect my simulations.

Can anybody please comment on that?


PS.- I know I could re-build the mesh and get rid of the low determinants, but this is not the point. I would like to understand their effect on the numerics.
amuzeshi likes this.
Zowie is offline   Reply With Quote

Old   April 5, 2011, 05:23
Senior Member
Andrea Ferrari
Join Date: Dec 2010
Posts: 319
Rep Power: 15
Andrea_85 is on a distinguished road
I have the same problem. Did you find any solution?

Andrea_85 is offline   Reply With Quote

Old   August 30, 2011, 09:40
Join Date: Nov 2009
Location: Germany
Posts: 96
Rep Power: 15
val46 is on a distinguished road
I'm also interested in this.
Has anyone some experience with this issue? Does this even effect the simulation?
"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   April 17, 2012, 13:26
Join Date: Mar 2009
Location: West London
Posts: 47
Rep Power: 15
anothr_acc is on a distinguished road
I'm interested too and can't find anywhere on this site that helps!

and then......

I realised the cells in question were extruded triangles; the extrusion resulted in all nodes of the wedges being in contact with a boundary condition: symmetry on one side, no slip on the other two: all nodes in each wedge are on a defined boundary. Perhaps that's the issue. They don't seem to be affecting solution too much.
holodeck10 likes this.
anothr_acc is offline   Reply With Quote

Old   November 25, 2019, 09:25
Senior Member
chandra shekhar pant
Join Date: Oct 2010
Posts: 216
Rep Power: 15
chandra shekhar pant is on a distinguished road
Dear All,

I am also facing the same issue, with "checkMesh" every thing is perfect and it says "Mesh OK". But with the "checkMesh -allTopology -allGeometry", it is showing "Failed 1 mesh checks" because of
***Cells with small determinant (< 0.001) found, number of cells: 210. (I assume).

Andsince my results are not converging for SIMPLE and for PIMPLE or/and interphasechangefoam they are crashing after a while (and if not crashing then they are stuck at a point).

I doubt that I will be able to make a better mesh. Does any one has found some thing in this context. If yes then please share, it will be a great help.

Thanks a lot!
chandra shekhar pant is offline   Reply With Quote

Old   April 20, 2021, 21:32
Senior Member
Claudio Boezio
Join Date: May 2020
Location: Europe
Posts: 137
Rep Power: 5
Ship Designer is on a distinguished road
To my surprise, I've noticed the same thing today as well. Especially interesting because I ran checkMesh -allGeometry on a case that I know to converge very well and it exhibits the same error. I took a look at the cells by running foamToVTK -cellSet underdeterminedCells and opening them with ParaView. The mesh is purely hexahedral and the only thing remarkable about those cells is that they are flat, i.e. at least one group of edges is considerably longer than the other two.

According to meshQualityDict:
//- Minimum normalised cell determinant. This is the determinant of all
//  the areas of internal faces. It is a measure of how much of the
//  outside area of the cell is to other cells. The idea is that if all
//  outside faces of the cell are 'floating' (zeroGradient) the
//  'fixedness' of the cell is determined by the area of the internal faces.
//  1 = hex, <= 0 = folded or flattened illegal cell
minDeterminant 0.001;
I don't understand this description and what it means for the numerical solution. It could be the Jacobian Determinant, according to this source at page 39, but I'm not sure.
ghastbug likes this.
Ship Designer is offline   Reply With Quote

Old   February 8, 2022, 12:51
Default info
Join Date: Mar 2018
Posts: 33
Rep Power: 6
ghastbug is on a distinguished road
I found this formula (attached image) on a snappyHexMesh pdf by Enggys, data at the bottom.

I don't understant what it means yet, but, it looks like A is the sum of the cell's areas, Ai is each face area, and tij is weird. I'm bad with component notation.

Edit: I made a 20x20x1 m plate in blockMesh, with 20x20x1 cells, and displayed the determinants on paraview. You can find it as an attached image. It looks like cell determinants depend on how many of the cell's faces touch boundaries, as opposed to how many cell faces are internal, and thus touch other cells. But I have no way to confirm it

(A Comprehensive Tour of snappyHexMesh
7th OpenFOAM Workshop
25 June 2012)
Attached Images
File Type: png determinant.png (96.3 KB, 43 views)
File Type: png determinantfoto.png (98.2 KB, 37 views)
Ship Designer likes this.

Last edited by ghastbug; February 9, 2022 at 04:19. Reason: new info
ghastbug is offline   Reply With Quote


determinant, mesh, pressure, quality, scheme

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to determine the direction of cell face vectors on processor patches sebastian_vogl OpenFOAM Programming & Development 1 October 11, 2016 14:17
Cells with t below lower limit Purushothama Siemens 2 May 31, 2010 22:58
How to determine the direction of cell face vectors on processor patches sebastian_vogl OpenFOAM Running, Solving & CFD 0 October 27, 2009 09:47
[Commercial meshers] Trimmed cell and embedded refinement mesh conversion issues michele OpenFOAM Meshing & Mesh Conversion 2 July 15, 2005 05:15
Warning 097- AB Siemens 6 November 15, 2004 05:41

All times are GMT -4. The time now is 03:37.