Thank you for the rapid reply!
It works!

Andreas


On 04/08/2011 11:23 AM, Ruth V. Sabariego wrote:
Hi Andreas,
You can use the internal function Boundary for finding the boundary lines of the surface and then the points.

Try the following example:

====================================
R = 1 ;
lc =  R/2 ;

Point(1) = {0,0,0,lc};

Point(2) = {R,0,0,lc};
Point(3) = {0,R,0,lc};
Point(4) = {-R,0,0,lc};
Point(5) = {0,-R,0,lc};

Circle(1) = {2,1,3};
Circle(2) = {3,1,4};
Circle(3) = {4,1,5};
Circle(4) = {5,1,2};

Line Loop(5) = {1,2,3,4};
Plane Surface(6) = {5};

list[] = Extrude {0,0,4*R} {
    Surface{6};
} ;
cylinder_volume = list[1];
cylinder_surface_top   = list[0];
cylinder_surfaces_side[]= list[{2:5}];

cylinder_lines_top[] = Boundary{Surface{cylinder_surface_top};};
cylinder_points_top[]= Boundary{Line{cylinder_lines_top[]};};
Characteristic Length {cylinder_points_top[]} = lc/10 ;

===================================
Regards,
Ruth


On 08/04/11 10:54, Andreas Puettmann wrote:
Hi everyone,

I want to mesh a cylinder (which I create by extrusion) with changing size elements. At one end I want to have smaller elements than at the other end. This is actually just the same problem as described here:
http://www.geuz.org/pipermail/gmsh/2010/005752.html

I know I can control the element size by adjusting the characteristic length:

Characteristic Length { expression-list } = expression;

But the question is: How can I obtain the numbers of points which were newly created by the extrude command? I.e. how should I specify expression-list?

As far as I understand, the extrude command only returns the IDs of the generated volume and surfaces. But I need points to specify characteristic lengths...

Any help is greatly appreciated.

Cheers
Andreas




--
Dipl.-Ing. Andreas Puettmann

German Research School for
Simulation Sciences GmbH
c/o Institute of Bio- and Geosciences 1
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