| Author | Message | |||
     Thomas Kuech (tfkuw) New member Username: tfkuw Post Number: 1 Registered: 12-2005 |
I am new to the program and I am trying a simple 3D problem with limited regions. I set it up but the program gives an error: 'mesh entangled near cell xxx'. I can't find in the manuals a clue to address the issue. Any suggestions? | |||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 505 Registered: 06-2003 |
FlexPDE allows you to say a lot of different things in your script, and unless I know what you said, it is difficult for me to guess what has happened. There is one known error in the processing of Limited regions: If you have two Limited Regions existing exclusively in adjacent layers, and if these regions overlap, then in the surface separating the layers, the regions will be treated according to the 2D rule that regions stated later in the script will overlay and hide parts of regions stated earlier in the script. This may cause the outline of the occluded region to be absent in the surface mesh, resulting in tangling of the 3D mesh. If one of these regions is totally contained in the other, then you can cure the problem by stating the larger region first in the script. If there is no total containment, you might be able to cure these troubles by making both regions present in both layers, assigning the appropriate material properties in the regions. Depending on your layout, this might merely cascade the trouble to the next layer. If neither of these things describes your case, you will have to send me the script so I can see what you are attempting to do. | |||
| Thomas Kuech (tfkuw) New member Username: tfkuw Post Number: 2 Registered: 12-2005 |
Thanks - it was an issue with but now I get a message: "Too many neighbors for (cell coordinates)". Any additional suggstions? I am attaching the script.
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| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 507 Registered: 06-2003 |
1. The mesh generator is having trouble making the transition from the very small size of the rod into the larger dimension of the enclosure. The default mesh generator settings allow triangular mesh cells on the bounding surfaces to be stretched into as much as 4:1 aspect. This sometimes causes trouble in filling 3D space. Use SELECT ASPECT=1 to force more nearly equilateral triangles on the bounding faces, and everything works ok. 2. Your regions 2 and 3 are identical. FlexPDE regions are based on projection of the figures into the 2D base plane. So regions 2 and 3 are really the same region. Move the LAYER definitions from region 3 to region 2 and remove region 3. (also remove the redundant second LIMITED REGION 3 statement). 3. Your requested initial timestep of 100 is much too large. Delete that part of the TIME statement, and let FlexPDE figure it out. Modified script attached.
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| Thomas Kuech (tfkuw) Junior Member Username: tfkuw Post Number: 3 Registered: 12-2005 |
Thanks for the advice and detailed explplanations. I appreciated the help. The system works as you indicated. I think I understand the layer/limited region bit more now as well as the mesh algorithms. tfk |
Heating element on pedestal in fluid media