[Gmsh] creating patch on sphere

[Peter Johnston]

Thanks Max and Christophe,

I have attached a simple sample .geo file. For some reason it creates even more volumes than the more complicated script I was working on. However, it still displays similar problems.

If you have any further questions, please let me know.

Thanks again,

Peter.

---------------------------------------------------------------------

Associate Professor Peter Johnston (FAustMS, FIMA)
School of Environment and Science
Griffith University | Nathan | QLD 4111 | Technology (N44) Room 3.19
T +61 7 373 57748| F +61 7 373 57656 Email p.johnston at griffith.edu.au
On 25 Apr 2019, 1:36 AM +1000, Max Orok <morok at mevex.com>, wrote:
Hi Peter,

Scripts are always helpful! It is nice to be able to see the steps as you go along.

Max

On Wed, Apr 24, 2019 at 8:36 AM Peter Johnston <p.johnston at griffith.edu.au<mailto:p.johnston at griffith.edu.au>> wrote:
Hello,

I appear to have a problem for which I cannot figure out a solution.

I have an annular hemispherical volume created between to hemispheres centred on the origin. I would like to divide the volume into two parts in a special way using Boolean operations. To define a sub-volume of the initial volume by defining four points on the surface of the inner sphere, create a “quadrilateral” on the inner surface by joining the four points in order using circles through the origin. (I think that these should be parts of great circles on the inner surface?). Then I create a line loop and a surface, and finally extrude the surface away from the origin to create a volume. Perhaps a .geo script would help here?

When I perform BooleanDifferences and BooleanIntersections I end up with three volumes instead of two. The reason I get the third volume is that the surface patch that I create does not fit exactly onto the original spherical surface. Is there any way that I can force the patch to be part of the spherical surface?

A consequence of the extra volume is that I cannot create a sensible mesh.

Any ideas would be greatly appreciated.

Thanks very much,

Peter.

PS, I could send a simple script file if that would help.

---------------------------------------------------------------------

Associate Professor Peter Johnston (FAustMS, FIMA)
School of Environment and Science
Griffith University | Nathan | QLD 4111 | Technology (N44) Room 3.19
T +61 7 373 57748| F +61 7 373 57656 Email p.johnston at griffith.edu.au<mailto:p.johnston at griffith.edu.au>
_______________________________________________
gmsh mailing list
gmsh at onelab.info<mailto:gmsh at onelab.info>
http://onelab.info/mailman/listinfo/gmsh<http://onelab.info/mailman/listinfo/gmsh>


--
Max Orok
Contractor
www.mevex.com<http://www.mevex.com>

[https://docs.google.com/uc?export=download&id=1fHTIiW4OMUjQr1iOkspQ7wiEsxunoOs0&revid=0B6x5w-5zVaEjSkpwbm5oY29jbG1XMzJoYldXTmJpNGFtb3dVPQ]
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://onelab.info/pipermail/gmsh/attachments/20190424/82a802dc/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: sample.geo
Type: application/octet-stream
Size: 2839 bytes
Desc: sample.geo
URL: <http://onelab.info/pipermail/gmsh/attachments/20190424/82a802dc/attachment-0001.geo>