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Denis Demchenko (denis)
New member Username: denis
Post Number: 1 Registered: 07-2006
| Posted on Wednesday, July 05, 2006 - 07:36 pm: | |
Hi, I understand how to make a sphere inside a cube. But to make a cube or cylinder inside a sphere seems more difficult. Is it possible? Thanks for any input.
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Robert G. Nelson (rgnelson)
Moderator Username: rgnelson
Post Number: 648 Registered: 06-2003
| Posted on Thursday, July 06, 2006 - 03:53 pm: | |
FlexPDE 3D uses a layered extrusion model to describe domain layouts. Anything you can conspire to represent in this way is legal (almost). The constraints are 1) that all dividing surfaces must be defined over the entire XY extent of the domain, 2) that dividing surfaces do not cross, 3) that all dividing surfaces are single-valued in (X,Y). Since part of the mesh generation process is done in the 2D projection of the figure, no dividing surface can be allowed to become vertical (the vertical waistband of a sphere succeeds because it is only "near-vertical" except exactly on the diameter). There would be several ways to represent a cube inside a sphere. One way would be to circumscribe a circle around the projection of the cube in (x,y). Then declare two conical internal dividing surfaces that meet the diamater of the sphere on the outside and the circumscribing circle at the top of the cube. The cones are mirror-image frustrums, cut off flat along the top of the cube.
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Robert G. Nelson (rgnelson)
Moderator Username: rgnelson
Post Number: 650 Registered: 06-2003
| Posted on Thursday, July 06, 2006 - 06:54 pm: | |
See the attached example script. I had to increase the size of the cylinder a little, because if it intersected the corners of the box, the mesh generator got confused.
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