Menu

Discussion Forum

New Discussion
Filter

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Creating Trees in Comsol

Posted Jul 19, 2012, 10:42 a.m. EDT Geometry, Mesh Version 5.0 5 Replies

Pavol Bauer
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi!

I have a funny model I'd like to try to construct: a 3d tree built from interconnected cylinders, say in relation to each other in a given angle or if simpler to imagine - as a fractal or real/biological tree!

A logical way to create this would be:
1) create Cylinder1(x,y,z,axis,length,diameter)
2) create Cylinder2 at the end of Cylinder 1 with some specific orientation
3) interconnect them at their endings so there are no "holes" in the face and the meshing works fine with any angle between them
4) optimally run this in a batch script - without manual editing!

But this doesn't work as there is no "fillet" method for objects in 3D and the intersection between the cylinders always creates problems for the meshing algorithm, which usually brakes at angles different then 90 and 270 degs..

Did someone encounter a similar problem (maybe when modeling connected pipes, or similar..) and could give me a hint how to do this best? I am thankful for any ideas or sources of inspiration :)

Paul
5 Replies Last Post Feb 18, 2015, 3:27 p.m. EST
Alexander Kuznetsov
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 19, 2012, 6:40 p.m. EDT
Try creating a circle and then sweeping it along a curved path.
Try creating a circle and then sweeping it along a curved path.
Ralf Tschiesche
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 20, 2012, 7:03 a.m. EDT
Hi!

Try to create a union with deactivated "keep interior boundaries".
Sometimes a sphere at the end of cylinder will also help...

Ralf
Hi! Try to create a union with deactivated "keep interior boundaries". Sometimes a sphere at the end of cylinder will also help... Ralf
Pavol Bauer
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 24, 2012, 11:35 a.m. EDT
Thanks Alexander and Ralf!

The sweeping along a path is actually a nice idea, it works well with straight lines but with curved paths it often dies with the error "Self intersections not supported".

Removing the inner boundaries on the other hand seems really robust so far, especially when joined with spheres on the connecting faces. I'm looking forward to see how it behaves when the geometrical complexity increases.

Thanks again to you & cheers
Paul
Thanks Alexander and Ralf! The sweeping along a path is actually a nice idea, it works well with straight lines but with curved paths it often dies with the error "Self intersections not supported". Removing the inner boundaries on the other hand seems really robust so far, especially when joined with spheres on the connecting faces. I'm looking forward to see how it behaves when the geometrical complexity increases. Thanks again to you & cheers Paul
Oscar Diaz
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 10 years ago Feb 18, 2015, 2:10 p.m. EST
Interesting challenge proposed by Paul. I require something similar (non-straight thin tubes), but get the same problem while trying to mesh 'the sweeping along a path': "Self intersections not supported", without been able to figure out WHAT DOES IT MEAN!!
The sphere-joints of 'cylinder segments' still bugs me because the union of elements (spheres+cylinders) creates a problem that do not let the geometry to be fully created, and when it finally works, the union point results with super small sections that kill the meshing...
Interesting challenge proposed by Paul. I require something similar (non-straight thin tubes), but get the same problem while trying to mesh 'the sweeping along a path': "Self intersections not supported", without been able to figure out WHAT DOES IT MEAN!! The sphere-joints of 'cylinder segments' still bugs me because the union of elements (spheres+cylinders) creates a problem that do not let the geometry to be fully created, and when it finally works, the union point results with super small sections that kill the meshing...
Walter Frei COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 10 years ago Feb 18, 2015, 3:27 p.m. EST
Hello Paul,

Creating trees is an interesting geometric question. With the new Design Module (www.comsol.com/design-module) you do have fillets available in 3D. The attached screenshot will give you some ideas about how you might create such a structure.

With respect to small features getting created during geometry creation, resulting in very small mesh elements: You will find Virtual Operations helpful here, for more details, please see: www.comsol.com/blogs/using-virtual-operations-simplify-geometry/

Lastly, if you want to create many different variations of a tree-like structure, you may be interested in the new Application Builder and Method editor. For more details, please see:
www.comsol.com/documentation/IntroductionToApplicationBuilder.pdf
Hello Paul, Creating trees is an interesting geometric question. With the new Design Module (http://www.comsol.com/design-module) you do have fillets available in 3D. The attached screenshot will give you some ideas about how you might create such a structure. With respect to small features getting created during geometry creation, resulting in very small mesh elements: You will find Virtual Operations helpful here, for more details, please see: http://www.comsol.com/blogs/using-virtual-operations-simplify-geometry/ Lastly, if you want to create many different variations of a tree-like structure, you may be interested in the new Application Builder and Method editor. For more details, please see: http://www.comsol.com/documentation/IntroductionToApplicationBuilder.pdf

Attachments:

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content