CFD Online Logo CFD Online URL
Home > Forums > Open Source Meshers: Gmsh, Netgen, CGNS, ...

gmshToFoam - insufficient geometrical tolerance?

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

LinkBack Thread Tools Display Modes
Old   March 17, 2011, 07:54
Default gmshToFoam - insufficient geometrical tolerance?
New Member
Will Logie
Join Date: Sep 2010
Location: ANU, Canberra, Australia
Posts: 21
Rep Power: 9
will.logie is on a distinguished road
Hallo fellow Gmshers,

I've recently stumbled across a warning in checkMesh and I'm not sure whether the problem indicated is leading to the problems I'm having in my simulations or not.

The gmsh I've created (see pic in attachments) is supposed to be a 2 wedge from a cylindrical water tank, and the holes represent a coil heat exchanger. My original thinking was that structured-hexahedra are preferable but with the simulation irregularities, I'm beginning to question this. In any case, I have parameterised the gmsh file for later optimisation.

But to return to the point, when I run checkMesh I get the following failure:
Wedge front with angle 1.00004 degrees
***Wedge patch front not planar. Point (0.260332 0.0457038 0.00454412) is not in patch plane by 3.73728e-08 meter.
Searching for the original point in the gmsh.msh file I find this likely suspect -> 8920 0.2603322947962474 0.04570379734961246 0.004544117108580378.

Is this warning to be taken seriously and if so, why doesn't gmshToFoam write a points file accurate enough?

If anyone can shed light otherwise, I'd be most thankful.
Attached Images
File Type: jpg gmsh.jpg (33.8 KB, 33 views)
will.logie is offline   Reply With Quote

Old   November 3, 2014, 12:58
Join Date: May 2012
Posts: 55
Rep Power: 8
styleworker is on a distinguished road
Maybe you have already solved your problem in the meantime.

For the sake of completeness: change writeFormat to binary in your controlDict before running gmshToFoam
styleworker is offline   Reply With Quote

Old   February 2, 2016, 09:10
Rudolf Hellmuth
Join Date: Sep 2012
Location: Dundee, Scotland
Posts: 40
Rep Power: 7
rudolf.hellmuth is on a distinguished road
gmsh saves the point positions with 16 digits of precision. gmsToFoam is truncating these big numbers, and thus making tiny shifts in the normal vectors of patch faces. Then the solver sees these tilts as non-planar. This problem doesn't occurs if the conversion is to binary data instead of ASCII.

I don't think these tiny point position shifts would impair your simulation.

I guess this problem could be solved in the source code of gmshToFoam with some sort of regularization of these truncation events.
rudolf.hellmuth 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
gmshToFoam problem. nilashansen Open Source Meshers: Gmsh, Netgen, CGNS, ... 11 June 5, 2016 10:45
GmshToFoam FOAM FATAL ERROR faces deallocated Tobias Prousa (Prousa) Open Source Meshers: Gmsh, Netgen, CGNS, ... 14 January 31, 2012 11:45
turbDyMFoam and Convergence lordvon OpenFOAM 5 September 25, 2010 21:18
[GAMBIT] gambit global geometric tolerance alireza2475 ANSYS Meshing & Geometry 1 July 19, 2010 01:23
stitchMesh for uncongruent patches (stitch tolerance) beugold OpenFOAM 0 June 18, 2009 07:38

All times are GMT -4. The time now is 00:51.