# Re: [Gmsh] Structured 2D mesh for structure more than 8 corners !

```Hi,

If I am not mistaken, the transfinite algorithm only handles 4-sided surfaces
so you will probably need to split your surface into rectangular blocks for it
to work. In that case, you are probably better using extrusions. See the
attached example and let me know if it helped.```
```
Guillaume DILASSER
Doctorant SACM / LEAS
CEA - Centre de Saclay - Bât.123 - PC 319c
91191 Gif sur Yvette Cedex - France -

guillaume.dilas...@cea.fr<mailto:guillaume.dilas...@cea.fr>

De : gmsh [mailto:gmsh-boun...@ace20.montefiore.ulg.ac.be] De la part de
Envoyé : mercredi 15 février 2017 14:41
À : gmsh@onelab.info
Objet : [Gmsh] Structured 2D mesh for structure more than 8 corners !

Dear all,

I am trying to make a structured mesh for following algorithm, but I could not
make it.
And my mesh is still unstructured !
Would you please let me know where I made a mistake ?
Many thanks,

this is my algorithm:
//**********************************
Point(1) = {0, 0, 0, 1.0};
Point(2) = {10, 0, 0, 1.0};
Point(3) = {10, 4, 0, 1.0};
Point(4) = {5, 4, 0, 1.0};
Point(5) = {5, 5, 0, 1.0};
Point(6) = {10, 5, 0, 1.0};
Point(7) = {10, 10, 0, 1.0};
Point(8) = {0, 10, 0, 1.0};

Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 5};
Line(5) = {5, 6};
Line(6) = {6, 7};
Line(7) = {7, 8};
Line(8) = {8, 1};

Line Loop(9) = {7, 8, 1, 2, 3, 4, 5, 6};

Plane Surface(10) = {9};
Physical Surface(11) = {10};

Transfinite Line {2}=5;
Transfinite Line {6}=6;
Transfinite Line {8}= 11;
Transfinite Line {7}= 11;
Transfinite Line {1}= 11;
Transfinite Line {3,5} =6;
Transfinite Line {4} = 2;

Transfinite Surface {10}={5,6,7,8,1,2,3,4};
Recombine Surface {10};

Again, thank you all,
Best,

```_______________________________________________