# [Gmsh] Gap between mesh and geometry

Jose A. Abell M. jaabell at ucdavis.edu
Fri Jan 30 18:18:32 CET 2015

```AFAIK, thats how it works. A way around for you is to split into 3 surfaces
by joining points 6 - 8 and 7 - 9. Then you can match the transfinite mesh
on those lines with that of your line 2. With this, you should have exact
geometry.

--

Jose Abell

On Fri, Jan 30, 2015 at 7:00 AM, Bulent Hatipoglu <
hatipoglu.bulent at gmail.com> wrote:

> If there is a discontinuity in one of the lines the Gmsh does not count it
> as a noddal point and a gap occurs between mes boundary and  geometry
> boundary.  Please see following figures for automatically generated and
> structured meshes  Is there a way to solve this issue?
> I think I can divide the geometry into separate surfaces or lines and mesh
> these separate surfaces/lines but this will be a workaround. I am looking
> for a better solution if available.
>
> Thanks,
>
> Bulent
>
>
> [image: Inline image 1]
> Automatic/unstructured
>
> [image: Inline image 2]
> Structured
>
> Codes used to generate these figures are here:
>
> Automatic /unstructured mesh:
> Point(1) = {100, 100, 0, 1};
> Point(2) = {200, 100, 0, 1};
> Point(3) = {200, 110, 0, 1};
> Point(4) = {100, 115, 0, 1};
> Point(5) = {103.5, 104, 0, 1};
> Point(6) = {150, 115, 0, 1};
> Point(7) = {170, 110, 0, 1};
> Point(8) = {150, 100, 0, 1};
> Point(9) = {170, 100, 0, 1};
> Line(1) = {1,8,9, 2 };
> Line(2) = {2, 3};
> Line(3) = {4,6,7, 3};
> Line(4) = {4, 1};
> Line Loop(6) = {3, -2,-1,-4};
> Plane Surface(6) = {6};
>
>
> Structured:
>
> Point(1) = {100, 100, 0, 1};
> Point(2) = {200, 100, 0, 1};
> Point(3) = {200, 110, 0, 1};
> Point(4) = {100, 115, 0, 1};
> Point(5) = {103.5, 104, 0, 1};
> Point(6) = {150, 115, 0, 1};
> Point(7) = {170, 110, 0, 1};
> Point(8) = {150, 100, 0, 1};
> Point(9) = {170, 100, 0, 1};
>
> Line(1) = {1,8,9, 2 };
> Transfinite Line {1} = 12 Using Progression 1;
> Line(2) = {2, 3};
> Transfinite Line {2} = 7 Using Progression 1;
> Line(3) = {4,6,7, 3};
> Transfinite Line {3} = 12 Using Progression 1;
> Line(4) = {4, 1};
> Transfinite Line {4} = 7 Using Progression 1;
> Line Loop(6) = {3, -2, -1, -4};
> Plane Surface(6) = {6};
> Transfinite Surface {6};
> Recombine Surface {6};
>
>
>
>
>
> _______________________________________________
> gmsh mailing list
> gmsh at geuz.org
> http://www.geuz.org/mailman/listinfo/gmsh
>
>
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```