Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
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.
geometry problems
Posted 18 mar 2013, 10:49 GMT-4 Geometry Version 4.3 2 Replies
Please login with a confirmed email address before reporting spam
Hi all,
My question is, if you build up a block first, then you build up a sphere inside the block.
Is it means that the volume which was belonged to the block is taken by the sphere?
If so, is it means that the surface of sphere is doubled? Since, I would expect that one is for the outer surface of sphere, one is for the inner surface of the block.
Thanks
Ferris
My question is, if you build up a block first, then you build up a sphere inside the block.
Is it means that the volume which was belonged to the block is taken by the sphere?
If so, is it means that the surface of sphere is doubled? Since, I would expect that one is for the outer surface of sphere, one is for the inner surface of the block.
Thanks
Ferris
2 Replies Last Post 18 mar 2013, 15:02 GMT-4
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Ferris-
Well, it depends on how you define your settings on the Finalize node at the end of your Geometry sequence.
I would recommend looking up the Boolean operations and the difference between "Form Union" and "Form Assembly."
In brief, "Form Union" will give you 1 boundary between the sphere and the block. "Form Assembly" will duplicate the boundaries. If you choose "Form Assembly", you will need to define how the domains will "communicate" mathematically.
Hope that helps.
Regards,
Josh Thomas
AltaSim Technologies
Well, it depends on how you define your settings on the Finalize node at the end of your Geometry sequence.
I would recommend looking up the Boolean operations and the difference between "Form Union" and "Form Assembly."
In brief, "Form Union" will give you 1 boundary between the sphere and the block. "Form Assembly" will duplicate the boundaries. If you choose "Form Assembly", you will need to define how the domains will "communicate" mathematically.
Hope that helps.
Regards,
Josh Thomas
AltaSim Technologies
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
do leanr to distinguish the geometrical objects = geohetrical shapes: cube and sphere, and the "analysed" FEM Entities: (domains, boundaries, and edges and points) . If you use the union mode, the sphere inside the cube will become two distinct domains: sphere and "cube - sphere" with one common boundary. If you use "assembly mode without imprints" you wil get two overlapping domains asphere and a cube, while the sphere volume is counted twice, and only external boundaries (unliked between the domains) for each of the two. If you use "Geometry mode Assembly with imprints" you will get implictely three domains, a combined one ((cube - shere) + sphere)) anda sphere plus two overlapping boundaries for the spheres, hrere too you will count the volume twice, and you need to use "identity pair" for the boundaries if you want continuity, and know how to handle the two spheres overlapping as this region will be meshed twice ...
Just to say "union" mode is the defalt and is easier to handle, implies single common boundaries with contiunuity of flux, except you you add some specific "thn boundary physics" whch "virtually split the boundary into two: an "up" and "down" side
--
Good luck
Ivar
do leanr to distinguish the geometrical objects = geohetrical shapes: cube and sphere, and the "analysed" FEM Entities: (domains, boundaries, and edges and points) . If you use the union mode, the sphere inside the cube will become two distinct domains: sphere and "cube - sphere" with one common boundary. If you use "assembly mode without imprints" you wil get two overlapping domains asphere and a cube, while the sphere volume is counted twice, and only external boundaries (unliked between the domains) for each of the two. If you use "Geometry mode Assembly with imprints" you will get implictely three domains, a combined one ((cube - shere) + sphere)) anda sphere plus two overlapping boundaries for the spheres, hrere too you will count the volume twice, and you need to use "identity pair" for the boundaries if you want continuity, and know how to handle the two spheres overlapping as this region will be meshed twice ...
Just to say "union" mode is the defalt and is easier to handle, implies single common boundaries with contiunuity of flux, except you you add some specific "thn boundary physics" whch "virtually split the boundary into two: an "up" and "down" side
--
Good luck
Ivar