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"free node" deletion problems: ANSA/TGRID

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Old   June 30, 2011, 17:28
Default "free node" deletion problems: ANSA/TGRID
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I just recently got a CFD job and am in the process of learning ANSA and tgrid.

I'm working on a basic project involving a car in a volume box to be later put in to fluent for Cd analysis.

I thought I completed my surface meshing over the car in ANSA (v. 13.1.3). The max skewness was down to about 86.3. When I tried to put this into TGRID, I found using "boundaries>nodes>count free nodes", that I had 13 free nodes. I went back to ANSA and used check>free>full DB and was able to find way more than 13 free nodes (50+) just floating in space (not sure how they got there). Interestingly, using ANSA's "check>free>visible" instead of full DB there were no free nodes. So I used ansa to "collapse" everything and was able to get rid of all free nodes. Now when I go through all ansa "check" menus, everything is green.

Going back into TGRID however, the 13 free nodes are still there. Using TGRID's "merge" function will not get rid of the problem even if i change the tolerance from 10^-5 to 10^-2. TGRID's Automesh should merge them if it can anyway i think. My goal is to somehow find out where these 13 are located. I don't know how to find the ID #'s for the free nodes in TGRID. Even if I did, the TGRID identifiers will not work in ANSA's "nodes>info>pick" function to manually find and delete each individual node. they must have a different node identifying scheme. Anyone have any ideas how to get rid of these nodes to complete my volume mesh? I'm new ANSA and TGRID...

Thanks!
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Old   July 5, 2011, 08:27
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Vangelis Skaperdas
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Hi there,

When you output from ANSA try to output in
Visible mode (not ALL or MODEL), while the GRIDs visibility flag is de-activated. In this way ANSA will only output the visible elements and only the nodes that use them.

FILE>Compress also helps in removing unnecessary nodes.

When you refer to max skewness I assume you mean
0.863 right? This is a bit high.
I assume you have started up ANSA in CFD mode, so if you switch to HIDDEN mode you will see all the elements that exceed fluent skewness >0.5.

If you use SHELL MESH>RESHAPE [Advanced] ANSA will fix most if not all of them.

Let me know if this helps.

Best regards

Vangelis
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Old   July 5, 2011, 15:11
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Hey thanks for the reply, I think Compress did the trick on most of them. The visibility trick will be good to know!

Thanks
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