# [Gmsh] rotational spline extrution.

Christophe Geuzaine cgeuzaine at ulg.ac.be
Sun Apr 12 22:27:55 CEST 2015

```> On 07 Apr 2015, at 05:55, Jaco Du Plessis <j.duplessis1 at uq.edu.au> wrote:
>
> Dear gmsh team,
>
> I Am trying to rotationally extrude a surface I have made between a line and spline. When i try I get the error, Could not find extruded vertex (..,..,..) i get this error about 700 times it seems that the edges are not being meshed for some reason. here is my script:
>

Indeed - it's a limitation of our extrusion algorithm: the lateral surface resulting from the extrusion needs to have 3 or 4 bounding edges (otherwise we don't know how to parameterize it). In this particular case, the lateral surface would only have two, hence it is not created. You will have to split the spline in at least two pieces...

> lc=0.1;
> Point(1) = {0, 0,  0,  lc};
> Point(2) = {0,0.25,-0.25,lc};
> Point(3) = {0,0.5,-0.5,lc};
> Point(4) = {0,0.25,-0.75,lc};
> Point(5) = {0,0,-1.0,lc};
> Spline(1)={1,2,3,4,5};
> Line(2) = {5,1};
> Line Loop(3)={1,2};
> Plane Surface (4)={3};
> Physical Surface("surf1") = {4} ;
> out[] = Extrude{ {0,0,-1}, {0,0,-1.0}, 2*Pi} {
>    Surface{4}; Layers{10,1}; Recombine;
> };
> Physical Volume(3)={out[1]};
> Mesh.CharacteristicLengthExtendFromBoundary = 1;
>
> I am using gmsh 2.8.4.
>
> Any suggestions would be appreciated.
>
> Regards,
> Jaco.
>
>
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--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine

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