[Gmsh] problem with 2D geometry representation?

[Hugh Blackburn]

Well, I found the error myself! Most of my points were not properly
defined in the plane... only 3, not 4, parameters.

Thx
Hugh

On Tue, May 11, 2010 at 3:01 AM, Hugh Blackburn
<hugh.blackburn at gmail.com> wrote:
> Hi there,
>
> Found something funny (or maybe I just did not understand) here. The
> following code draws a segment of a circle as an inner part and out
> part (the curves are drawn using Circle).  But the arcs seem
> distorted: when I draw two points that ought to lie on the arcs
> (Points 6 and 7) they are visibly away from the curves. I found this
> also when I tried to use extrude to do the generation: the curves that
> came out of Extrude did not match those drawn by Circle. What is
> wrong?
>
> (I have left off the parts of the file associated with meshing: I'm
> still worried that the geometry is incorrect.)
>
> TIA
> Hugh
>
> // -- 2D mesh algorithm: 1=MeshAdapt, 5=Delaunay, 6=Frontal
> Mesh.Algorithm=1;
>
> // -- All-quad mesh:
> Mesh.SubdivisionAlgorithm=1;
>
> lc1 = 0.1;
> lc2 = 0.1;
> rad = 0.5;
> san = Pi/5.;
>
> Point(1) = {0, 0, 0, lc1};
> Point(2) = {-0.8*rad*Sin(san), -0.8*rad*Cos(san), lc2};
> Point(3) = { 0.8*rad*Sin(san), -0.8*rad*Cos(san), lc2};
> Point(4) = {-1.0*rad*Sin(san), -1.0*rad*Cos(san), lc2};
> Point(5) = { 1.0*rad*Sin(san), -1.0*rad*Cos(san), lc2};
>
> Point(6) = {0, -0.8*rad, lc2};
> Point(7) = {0, -rad, lc2};
>
> Line(1)   = {2, 1};
> Line(2)   = {1, 3};
> Circle(3) = {2, 1, 3};
> Line(4)   = {4, 2};
> Line(5)   = {3, 5};
> Circle(6) = {4, 1, 5};
>
>
> --
> Hugh Blackburn
> Associate Professor
> Department of Mechanical and Aerospace Engineering
> Monash University
> Vic 3800
> Australia
> Building 31, Rm 119
> Tel: +61-3-9905-1828
> Fax: +61-3-9905-3558
> mailto:hugh.blackburn at eng.monash.edu.au
> http://users.monash.edu.au/~bburn
>



-- 
Hugh Blackburn
Associate Professor
Department of Mechanical and Aerospace Engineering
Monash University
Vic 3800
Australia
Building 31, Rm 119
Tel: +61-3-9905-1828
Fax: +61-3-9905-3558
mailto:hugh.blackburn at eng.monash.edu.au
http://users.monash.edu.au/~bburn