# [Gmsh] Unable to create Simple Mesh

Vincent Huber vincent.huber at cemosis.fr
Wed Feb 24 08:54:37 CET 2016

```Hello Vikram,

I’m afraid your lines are mixed up.

What di you think of the following ?

h=0.1;
p1 = newp; Point(p1) = {0, 0, 0, h};
p2 = newp; Point(p2) = {0, 1, 0, h};
p3 = newp; Point(p3) = {-0.35, 0, 0, h};
p4 = newp; Point(p4) = {2, 0, 0, h};
p5 = newp; Point(p5) = {-0.35, 1, 0, h};
p6 = newp; Point(p6) = {2, 1, 0, h};
l1 = newl; Line(l1) = {p1, p3};
l2 = newl; Line(l2) = {p3, p5};
l3 = newl; Line(l3) = {p5, p2};
l4 = newl; Line(l4) = {p2, p6};
l5 = newl; Line(l5) = {p6, p4};
l6 = newl; Line(l6) = {p4, p1};

ll1 = newll; Line Loop(ll1) = {l1,l2,l3,l4,l5,l6};
s1 = news; Plane Surface(s1) = {ll1};

Physical Line("front") = {l1,l2,l3};
Physical Line("bottom") = {l4,l5,l6};

Physical Surface("Omega") = {s1};

​

2016-02-23 16:42 GMT+01:00 Vikram Singh <vikramsingh001 at gmail.com>:

> I am unable to create a simple 2D mesh.
>
> I need to create a structured mesh for a rectangular domain.
>
> I divide the domain into two parts. I want different boundary conditions
> on the bottom part for the front part and the part behind.
>
> Point(1) = {0, 0, 0, 0.1};
> Point(2) = {0, 1, 0, 0.1};
> Point(3) = {-0.35, 0, 0, 0.1};
> Point(4) = {2, 0, 0, 0.1};
> Point(5) = {-0.35, 1, 0, 0.1};
> Point(6) = {2, 1, 0, 0.1};
> Line(3) = {1, 3};
> Line(4) = {3, 4};
> Line(5) = {5, 2};
> Line(6) = {2, 6};
> Line(7) = {3, 5};
> Line(9) = {4, 6};
>
> Now, GMSH stops making sense after this.  I try to create a plane surface
> and this is what GMSH does.
>
> Line Loop(10) = {4, 9, -6, -5, -7};
> Plane Surface(11) = {10};
>
> As you can see, 3 is not there in the line loop. And the mesh completely
> ignores Point 1.
>
> What is happening?
>
> Vikram
>
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> gmsh at onelab.info
> http://onelab.info/mailman/listinfo/gmsh
>
>

--
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