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-   -   [ICEM] Blocking Strategy (http://www.cfd-online.com/Forums/ansys-meshing/64947-blocking-strategy.html)

hubidoo May 29, 2009 08:04

Blocking Strategy
 
...

Hey,

I would like to use hexa mesh for the attached part. But I can´t find a opportunity to split an merge the block for the two outflows.

Chance with interfaces or anything else? Haven´t found anything...

Thanks!
Eric:)

PSYMN May 29, 2009 10:06

Blocking is Elastic, think in terms of blocking topology rather than geometry shape..
 
I am not sure what you mean about merging, but I think you could block this all at once if you wanted… You need to think in topology shape rather than geometry shape… Separating this in your mind is important for blocking convoluted geometries.

Imagine that the ring is elastic and stretch it to the right and twist it so that it forms a ring around the inner cylinder with radial tubes (not slanted) connecting it to the central cylinder. The pipe connected to the side of the ring (currently at the middle of the left side) would twist 90 degrees and be pointed toward the right side… Am I being clear enough?

Anyway, if you think of this in terms of topology rather than shape, it becomes a simpler setup of concentric rings and right angle connections which are much easier to block… Of course you end up fitting the blocking to the real geometry to simulate your actual flow…

PSYMN May 29, 2009 10:08

Hands on help...
 
To show you what I mean, I would be willing to block this section quickly for you if you sent the tetin file...

Simon

hubidoo May 30, 2009 05:00

PSYMN, thanks for your help!

It´s difficult to imagine your suggestion:o
Attached you will find the tetin file

PSYMN May 31, 2009 22:42

When I can...
 
I will try to take a look monday or tuesday evening.

PSYMN June 3, 2009 11:12

Here you go...
 
5 Attachment(s)
Hello Eric,

Last night I blocked it as described, but didn’t have a good connection to upload until now…

I was in a rush (took about half an hour) so I didn’t take much care with the 2 connector pipes, but you can see what I did and trim the blocks to fit properly… It may be that you didn’t intend to have the little pipe touch the edge of the ring on one side, but not the other… So I didn’t want to waste time on that… I also didn't align everything to make it pretty, this was just to give you the idea of how it should be blocked.

I included a replay file and a new tetin file (with some parts I could turn off). I had to spread these over two zip files to keep them under 100k each. Hopefully you know how to use a replay file and hopefully you can learn to view things with their topological shape…

In the end I put an OGRID thru everything…

I will try to attach some screen shots from along the way.

PSYMN June 3, 2009 11:14

Few More images...
 
2 Attachment(s)
Here are a couple more screen shots...

hubidoo June 3, 2009 11:33

Quote:

Originally Posted by PSYMN (Post 218141)
I was in a rush

wow, it is awesome...give me some time to understand...:)

hubidoo June 4, 2009 13:23

1 Attachment(s)
Hello,

I am stuck again.:o
I tried what you have told me and it works fine!
Now I try to mesh the inflow and outflow.
But I am not able to create a good blocking sturcture.
Could you give me a advice?

Eric

PSYMN June 5, 2009 10:56

Sub Topologies...
 
Maybe just block those separately and then merge the sub topologies...

The only catch is that you should make sure the topology is the same where the blocking files will meet (such as an Ogrid topology in your case (8 verts in 2 concentric boxes).

You will do it by creating blocking for each of the three sections independently (one blocking file at a time). Then load all three blocking files with the geometry and it will ask you if you want to merge or replace, chose merge. They will go into the Blocking branch of the tree under "Topologies". You can only view one at a time.

Starting with the largest one displayed, go into the topologies branch and merge topologies. Select the other two blocking files to merge with the root.

If the verts were close enough, they will be merged (based on the tolerance). Other wise, just use "merge verts" and do it manually. Once all 4 verts of a block are merged, the face between them is considered merged... Take care of all the interfaces and you will be done...

Warning, this does muddle your index control, so make sure you are happy with each blocking on its own first as it gets harder to work when the index is muddled.

Simon


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