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-   -   [ICEM] Merging free nodes (http://www.cfd-online.com/Forums/ansys-meshing/67295-merging-free-nodes.html)

jsm August 11, 2009 08:38

Merging free nodes
 
Hi,

I am doing patch dependent surface meshing for complex geometry to get good quality surface meshing. Geometry is dirty one. Geometry has single edge surfaces (yellow colour) for some parts.

After surface mesh generation, I tried to connect free nodes using merge node with tolerance option. I tried many times with big tolerance also . But I could not succeed. How can I to connect these free nodes? Is there is any other way to follow?

PSYMN August 12, 2009 10:31

Lots of options...
 
There are always lots of options with ICEM CFD...

I owuld start by going back to the geometry and trying a larger tolerance with build topo... If you can get those yellow curves to turn red, you save your self some trouble. Defintily try this if you have a lot of yellow edges... If you need more explanation about how build topo works, let me know...

If you still have yellow curves and merge with a tolerance is failing, it is probably because of projection of those curves... Turn on the option to "ignore projection".

If that fails, then mesh as you did and use the interactive mesh merging (one node at a time) to merge the last few elements on each side of the gap.

If this results in what looks like a hole (at least a mesh unit wide) then use Repair => mesh from edges. make sure to turn of projection if you don't have a surface there.

If the remaining gap looks more narrow (less than an element wide) you could use the "stitch edges" command to sew things together.

jsm August 13, 2009 05:03

Hi Simon Pereira,

Thanks for your reply. I will follow your suggestions and get back to you if I have trouble.

Also I have one more doubt. Is it possible to know the tolerance of imported geometry before using "build topology" command. It is more useful for this kind of situations.

Thanks in advance for your suggestions.

PSYMN August 13, 2009 08:56

build topo
 
Because Build Topology can sometimes cause trouble, I do usually check if I need it before running it...

On the left side of the screen in the model tree, right click on "curves" and turn on the option for "color by count". This colors the curves without running topology.

If you mean to ask how to determine what the tolerance should be... I usually just use something like 1/4 or 1/10th of my smallest mesh size. If you want to be more careful about it, find a pair of yellow curves and use the measure tool (top left corner, second row) to find out how far apart they are... Use something approximately double that...

jsm August 16, 2009 23:58

Hi Simon Pereira,

Thanks for your help.


Your reply is more informative and clears my doubt.:D


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