# [Gmsh] 3D mesh crash. Coplanar points warning

Benjamin SAUTHIER sauthierbenjamin at yahoo.fr
Sun Sep 25 13:35:47 CEST 2005

```Hello,

I want to mesh a domain bounded by a 2m long cylinder
inside an approximately 20*20*25m box.

The surface mesh of the cylinder is generated by
extrusion of a circle (Transfinite mesh) to obtain

The characteristic length is max 0.5m at the boundary
of the box and min 0.06m on the cylinder.

When generating the 3D mesh I got the  warnings of
coplanar points and "Unable to add points" statements.
Ultimately gmsh crashes.

I looked at changing characteristic length and random
perturbation factor but it didn't work. Where does
this come from? Is there a workaround beside using
Netgen (this mesh is actually a stripped down version
of a bigger mesh with mixed hexa and tetra elements).

I joined the geo files.

Thx for you help.

Benjamin

------------------------------

Info    : Meshing surface 66
Info    : Smoothing surface 66
Info    : Meshing surface 68
Info    : Smoothing surface 68
Info    : Mesh 2D complete (0.793879 s)
Info    : Mesh 3D...
Info    : Mesh 3D... (initial)
Info    : Nod=645/12914 Elm=2600
Info    : Vol=16464 (346 297 2)
Info    : Nod=1290/12914 Elm=5185
Info    : Vol=16464 (662 625 3)
Info    : Nod=1935/12914 Elm=9473
Info    : Vol=16464 (846 1085 4)
Info    : Nod=2580/12914 Elm=14224
Info    : Vol=16464 (1374 1202 4)
Info    : Nod=3225/12914 Elm=17741
Info    : Vol=16464 (1940 1281 4)
Info    : Nod=3870/12914 Elm=21113
Info    : Vol=16464 (2508 1357 5)
Info    : Nod=4515/12914 Elm=24365
Info    : Vol=16464 (3078 1432 5)
Warning : Coplanar points in circum sphere computation
Warning : (3.05,3.59187,20.1245) (3.05,3.575,21.866)
(3.05,3.46624,21.7934) (3.0
5,3.575,20.134)
Warning : Coplanar points in circum sphere computation
Warning : (3.05,3.69232,21.9239) (3,3.69232,21.9239)
(3,3.575,21.866) (3.05,3.57
5,21.866)
Warning : Unable to add point 3175 (will try it later)
Warning : Unable to add point 3135 (will try it later)
Warning : Unable to add point 3095 (will try it later)
Warning : Unable to add point 5055 (will try it later)
Warning : Unable to add point 161 (will try it later)
Warning : Unable to add point 351 (will try it later)
Warning : Unable to add point 1015 (will try it later)
Warning : Unable to add point 1055 (will try it later)
Warning : Unable to add point 2975 (will try it later)
Warning : Unable to add point 1095 (will try it later)
Warning : Unable to add point 1135 (will try it later)
Warning : Unable to add point 2935 (will try it later)
Warning : Coplanar points in circum sphere computation
Warning : (3.05,4.34625,20.0375) (3,4.31237,20.0286)
(3.05,4.31237,20.0286) (3,4
.34625,20.0375)
Warning : Unable to add point 2895 (will try it later)
Warning : Unable to add point 2855 (will try it later)
Warning : Unable to add point 2815 (will try it later)
Warning : Unable to add point 306 (will try it later)
Warning : Coplanar points in circum sphere computation
Warning : (3.05,4.84666,20.364) (3.05,4.77895,20.2898)
(3.05,4.81205,20.3242) (3
.05,3.575,21.866)
Warning : Coplanar points in circum sphere computation
Warning : (3.05,4.84666,20.364) (3,4.81205,20.3242) (3.05,4.812

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