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catrapi December 1, 2012 13:19

Help mesh a pipe cross
Hello everybody,

I'm sorry to post this here, but i've been searching for a while and i can't do this properly. I need to study the flow within a pipe cross like this:
But i can only get this type of mesh, which i believe is not the best one:
I read about blocking and separating the part at the junctions, but i don't know how to do it in desingmodeler.
I also need to do it with three pipes crossing. I really need your help.

Thank you so much in advance!

diamondx December 1, 2012 14:38

take a look here, hope it can help you

catrapi December 3, 2012 06:01

Thank you for the answer.

Just another question: So I don't need to divide the geometry in DM because the multizone does that for me? Even if it is a bit more complex than just a simple tube? And is the mesh that I have now, good?

Thank you

catrapi December 3, 2012 06:04

I found this:

Should I try and do this in DM?

diamondx December 3, 2012 13:56


So I don't need to divide the geometry in DM because the multizone does that for me?
Best way to find out is to try, not sure of all the capabilities of Ansys meshing...

About the link you sent me, this is done using Gambit, it can also be done using ICEM CFD.
Start working on that if you want, there are good tutorial and training material that can help do that, it doesn't take too much time... we can assist you too

catrapi December 5, 2012 12:07

I've been reading the tutorials and it says that multizone automatically decomposes the geometry. I've tried decomposing myself and it then sweep it, but i found that the elements grew worse than with multizone. So i believe this is the best method.
Thanks diamondx for helping me! :)

jrunsten December 6, 2012 07:51

Lots of slicing in DesignModeler together with Multizone meshing will produce the following. It's faster in ICEM if you know it, otherwise it may be a good choice for you.

catrapi December 7, 2012 05:04

jrunsten, thank you so much!
In fact when I use multiblock, the mesh in the middle becomes triangular
instead of quad. And I read it should be quad in order to get best results. How did you decide where to slice the part? I mean the dimensions? Is it a "more or less like this", or do you have specific places where to slice?

Once again, thank you!

jrunsten December 7, 2012 05:39

This was just some random dimensions i chose, but basically it is all scliced using planes rotated 45 degrees about the origin and then I merged the resulting pieces into the bodies i wanted. Don't forget to create a new part from the final bodies. The only dimension I set for this is the size of the square in the middle.

In ICEM, i guess this would correspond setting the size of the ogrid.

You can my files here:
Maybe it can help someone

Far December 11, 2012 03:41

@jrunsten Good work. I have two queries:

1. How did you get the hexa meshing at the interface of four pipes (or intersection of two pipes)

2. How to make the wbpz workbench file.

jrunsten December 11, 2012 03:55


Originally Posted by Far (Post 396826)
@jrunsten Good work. I have two queries:

1. How did you get the hexa meshing at the interface of four pipes (or intersection of two pipes)

2. How to make the wbpz workbench file.

1. It's all in the splits. See the image below. Every part in the multibody cosists of 90 degree bends, making it easy for the Multizone meshing to work

2. In Workbench, choose File>>Archive. The option to restore an archive is directly below.

Far December 11, 2012 04:05

version 14.5 :o I have 14 so not possible for me to use it (your project uploaded in previous post).

jrunsten December 11, 2012 04:10

Ah ok,

Well I think all the info is here anyway. Perform the slices with your preffered method, create a multibody part and then mesh them all together with a multizone method. For fine grid at the walls, right click the Multizone method and choose "Inflate this method". Choose the correct wall surfaces for each inflation instance and it should work just fine.

catrapi December 11, 2012 04:44

Hi, I have version 13, so I'm not able to open.
I tried to split the body, and I can, but I get a lot of parts, and then I'm not able to merge some parts back together (in DesignModeler). Can you please explain to me how you do that?
Thank you!

jrunsten December 11, 2012 04:47

Create>>Boolean, Unite

catrapi December 11, 2012 05:32

Thank you so much for all your help! I managed to divide it. It took me a while! Thank you

catrapi December 11, 2012 09:59


I don't know if it was posted before, but I can't find it. Is there anyway that I can do a mesh just to one and then replicate it in others? Like if I want these 4 of these crosses connected, can I make a mesh just for the first cross and then make a pattern to mesh the following crosses?

jrunsten December 11, 2012 10:40

Not that I'm aware of. You can certainly make a pattern of the geometry in DM, but not in meshing. A bit more work meshing four of them, but not that much.

catrapi December 11, 2012 11:10

I did it in DM, but when I try to mesh it, it takes forever, and I end up stoping the mesh... Is there any way I can speed it up?

jrunsten December 11, 2012 11:23

Four in a row or 2x2 like a square?

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