[Gmsh] 2D structured mesh in gmsh

[Maciej Piechotka]

Hi,

Sorry for asking probably very basic question, but despite trying, reading
several tutorials etc. I have problems with created 2D structured mesh (probably
because I have no idea what actually extrude does).

I simply need to include graphics comparing unstructured and structured mesh in
report (later in thesis). I created a simple mesh:

Point(1) = {0, 0, 0, 1.0};
Point(2) = {0, 1, 0, 1.0};
Point(3) = {1, 1, 0, 1.0};
Point(4) = {1, 0, 0, 1.0};
Point(5) = {0.5, 0.5, 0, 1.0};
Point(6) = {0.75, 0.5, 0, 1.0};
Point(7) = {0.25, 0.5, 0, 1.0};
Circle(1) = {7, 5, 6};
Circle(2) = {6, 5, 7};
Line(3) = {1, 2};
Line(4) = {2, 3};
Line(5) = {3, 4};
Line(6) = {4, 1};
Line Loop(7) = {3, 4, 5, 6};
Line Loop(8) = {2, 1};
Plane Surface(9) = {7, 8};

Creating unstructured mesh in gmsh was trivial - however when I tried to
followed demos/hex.geo example suddenly the mesh started behave
strangely (for example suddenly parts move outside volume [from what
I understend I need to partition 3D]). How can I mesh the above surface?

Thank you very much for help (the only people using gmsh I have access to work
on unstructured meshes and I need to create mesh just for my report). 

Best regards