# "gmsh" returns 2D result for 3D model

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## "gmsh" returns 2D result for 3D model

 This post was updated on . [Oct 17, 2020: I have discovered that this issue and the one posted as '"Missing "Rotate 3D" icon' are indistinguishable (at least by me). Here is what I think I have found: gmsh returns a 2D result for this geometry and it is displayed in a 3D context - can be rotated and zoomed as if it were a very thin 3D model.  However, if the model is saved as a model file (.fea) and the re-opened, it is displayed as a 2D figure, thus with no "Rotate 3D" control. So from my perspective there are two issues:  First, what is it about the geometry that causes gmsh to return this seeming 2D model with a "grid cell mean quality" of "NaN" or "Inf"? The second issue is the way FEATool handles/displays this case both when it happens and after it is saved and reloaded. I have added another post to this issue with an example that is captured from the ground up that will re-produce both issues from scratch. See below.]This issue may well be caused by my ill formed model.  But I submit it in hopes of at least learning where the problem lies. It is similar to one provided in the second entry of the "Missing "Rotate 3D" icon" post: http://forum.featool.com/Missing-Rotate-3D-icon-tp831p832.html The geometry is an elliptical disk that has been chamfered twice and then is is enclosed in a block. Here are the model, gui, and MATLAB script files. gmshPlanarResult.feagmshPlanarResult.fesgmshPlanarResult.mHere is what the disk looks like inside the block: When submitted to gmsh, here is the result: Some time after I had moved on from the occurrence of this issue, I noticed the following error indications in the MATLAB Command Window, so I cannot be sure that they were associated with the creation and processing of the model, but I am including them in case they provide useful information: gmshPlanarResult.txtKinid regards, Randal
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## Re: "gmsh" returns 2D result for 3D model

 This post was updated on . The case in this post will reproduce this issue ' "gmsh" returns 2D result for 3D model' and 'Missing "Rotate 3D" icon' found at: http://forum.featool.com/Missing-Rotate-3D-icon-tp831.html . Use these steps: 1. Create a new 3D model, Conductive Media. 2. Create 2D Workspace at (0,0,0) 3. Create an Ellipse x=.05, y=.1 4. Extrude 0.02 along 'z' axis 5. Chamfer 0.005 6. Chamfer 0.002 7. Create a block -2:2 -1:1 -1:1 ... to produce this model geometry: 8. Generate grid using 0.21 (default) ... to produce a normal 3D grid: Changing to the Geometry mode and zooming in on the 20mm thick disk: 9. Reduce 'z' dimenson of elliptical disc by transforming scale [1  1 .05]. ...shrinks the disk in thickness ('z') by a factor of 20: [So far everything seems normal. Problems begin to appear with the next step.] 10. Generate grid using grid size of 0.21 (default) ... to produces a 3D displayed grid that seems to be only 2D (in x, y): Note FEATool Command log showing "grid cell mean quality: Inf". 11. At this point save Model, GUI Script, and MATLAB script files: bladeInTankThinGrid.feabladeInTankThinGrid.fesbladeInTankThinGrid.m12. Finally open the Model file just saved (bladeInTankThinGrid.fea) and observe a 2D figure grid with no "3D Rotate" icon: Kind regards, -Randal
 Administrator Most likely Gmsh has produced a mesh with poor quality cells, if you look back at the Gmsh log ouput you will probably see lines like this Warning: ill-shaped tets are still in the mesh Info: 0.00 < quality < 0.10 : 228 elements The mesh might still be ok to compute with depending on the purpose. The best way to tell is to actually try to use it.