# [Gmsh] 3D meshing won't work

Christophe Geuzaine geuzaine at acm.caltech.edu
Wed May 5 06:13:28 CEST 2004

```Magdalena Stolarska wrote:

> Hi.  I have a few of questions.  I apologize if they are elementary --
> I'm fairly new to this and have a hard time finding an explanation on the
> web.
>
> 1) What exactly is consistent elementary surface orientation (as described
> under the Surface Loop explanation in the documentation of Gmsh 1.51)?
>
> 2) I've attached the *.geo file that I am working on -- For some reason,
> the 2D surface meshing works okay, but the 3d meshing is not working (I
> just end up with a 2d mesh).  Depending on what I choose the
> characteristic length to be, I get a variety of complaints.  For example,
> for a characteristic length of 0.1, I get no complaints other than one
> error: "Error : No contour".  For a characteristic length of 0.05 I get
> complaints like (in addition to the one above)
> Error : Missing edge without any intersection (0.55,0.1,0.3) (0.55,0,0.3)
> and
> Warning : *Unrecoverable* face (0 <--> 1=2*(3-1)-3)
> For a characteristic length of 0.04 the only error I get is "Error : No
> contour".
>
>>From the little that I know gmsh, I am thinking that the fact that there
> is no 3d mesh has to do with either the surface loop ordering or the
> error:"Error : No contour".  I checked all of my Line Loops, and the
> ordering seems okay, so could you at least please let me know what the no
> contour error could mean.  Any other suggestions would also be greatly
> appreciated.  Thank you.

The definition of the line loop 74 is wrong:

Line Loop(74) = {22,23,-47,45,48,25,26,27,28};

should be replaced with

Line Loop(74) = {22,23,-47,45,48,25,26,27,28,21};

PS: You should use the graphical user interface to construct your loops:
it makes the whole process soooo much easier...

--
Christophe Geuzaine
Applied and Computational Mathematics, Caltech
geuzaine at acm.caltech.edu - http://geuz.org

```