# [Gmsh] Extruding a circle into a cylinder

johannes.wagner at gmail.com johannes.wagner at gmail.com
Mon Feb 29 11:53:20 CET 2016

```I have a short follow up question on this: Is it possible to get the
cylinder walls as a Compound surface, i.e. not divided by the 4 lines that
come from the <pi circle arc extrusions? Right I now don't have an idea how
to do this...

Hope

On Monday, September 9, 2013 at 5:33:12 PM UTC+2, Sacconi, Andrea wrote:
>
> Hi everybody,
>
> I have a problem with the Extrude command.
> I would like to create a cylindrical mesh, but I need to generate a mesh
> only on the lateral surface of the cylinder. In other words, I don't want
> any elements on the two circles, top and bottom.
>
> I wrote this:
>
> lc = 0.5;
> Point(1) = {-1, 0, 0, lc};
> Point(2) = {0, -1, 0, lc};
> Point(3) = {1, 0, 0, lc};
> Point(4) = {0, 1, 0, lc};
> Point(5) = {0, 0, 0, lc};
> Circle(1) = {1, 5, 2};
> Circle(2) = {2, 5, 3};
> Circle(3) = {3, 5, 4};
> Circle(4) = {4, 5, 1};
> Line Loop(5) = {1, 2, 3, 4};
>
> geoExtrude[] = Extrude {0, 0, 1} { Line{5}; };
>
> but I don't get any extrusion. I see only the circle centred at (0, 0, 0)
> Is it possible to get the cylinder I need? How would you proceed?
>
>
> Andrea
>
> __________________________________________________________
>
> Andrea Sacconi
> PhD student, Applied Mathematics
> AMMP Section, Department of Mathematics, Imperial College London,
> London SW7 2AZ, UK
> a.sac... at imperial.ac.uk <javascript:>
>
> _______________________________________________
> gmsh mailing list
> gm... at geuz.org <javascript:>
> http://www.geuz.org/mailman/listinfo/gmsh
>
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