[despaired student]

So, did an improved blocking but there are still some bad regions remaining (see attached picture).
Therefore I would create some more Block-segments within these rings and regions. That should pick up the strongly unequal distribution of nodes along the neighboring blocks of the different rings.

[despaired student]

So my last try for this day -> it's close to perfection

[Far]

Cool. In fact I have learned many things from you, while working on your problem.

PSYMN's comments are ultimate and gives in depth understanding of ICEM CFD.

[despaired student]

Hi,

the model looks good so far. It's good that you also learned something, Far, maybe not as much as I did but started from different levels. Can you also help me with the next problems?

I tried to rotate the blocking to have the entire top-side blocked and to be ready to extrude the blocking into 3D.

Is there a way to rotate the 2D blocks and ensure that the rotated ones are associated correctly?

-->"Blocking - Transform Blocks - Copy Periodic Blocking " didn't work.
For this I set the angle in "Mesh - Global Mesh Setup - Setup Periodicity; Type: Rotational Periodic; Method: User Defined by angle" to values of 180° or 90° or 45° or 0°. For the 90° angle the Geometry and the blocking was copied to bottom-right quarter with correct associations.
But how can I do this for the left-bottom quarter?


Regards

[Far]

Is there a way to rotate the 2D blocks and ensure that the rotated ones are associated correctly?

Rotate (copy option enabled) the blocking by 90 deg and also copy the geometry (points, curves, surfaces) and simply click update associations. This is the best solution as learned from PSYMN's suggestions.

For this I set the angle in "Mesh - Global Mesh Setup - Setup Periodicity; Type: Rotational Periodic; Method: User Defined by angle" to values of 180° or 90° or 45° or 0°. For the 90° angle the Geometry and the blocking was copied to bottom-right quarter with correct associations.
But how can I do this for the left-bottom quarter?

This isn't necessary at the moment. For 180 deg model we shall use symmetry condition.

I tried to rotate the blocking to have the entire top-side blocked and to be ready to extrude the blocking into 3D.

Only consideration needed is; cut the model into half such that you get the half in and out pipes.

[despaired student]

Very good it's working. I was trying and searching for quite some time...sometimes this program can be very frustrating...
So what is this periodicity-setup for? Can I use it to tell the solver that the left half of my model behaves like the right halft?

Thanks again Far!

[Far]

Very good it's working. I was trying and searching for quite some time...sometimes this program can be very frustrating...

So what is this periodicity-setup for?

This is to setup the periodic model so that you get the one-one mapping to implement the periodic boundary condition in Fluent and or any solver. For your problem, symmetry condition is appropriate.

Can I use it to tell the solver that the left half of my model behaves like the right half

Yes this is the concept of periodicity.

[PSYMN]

Periodicity is useful when you have periodic boundary conditions and don't want to model the entire domain. Often modeling one segment of the domain is sufficient and the solution will converge in much less time.

But overall, you guys are on the right track... Good work.

[despaired student]

Hi,
in a blocking ICEM gave me a very strange quality-picture. Maybe you know what's wrong, what I should do instead and why the elements are arranged in that strange way...?
At one pipe you can see the problem at the other pipe I improved it a bit.

Again I have a model with 2 Pipes (see .tin file). My aim was to mesh the pipes plus the cylinder and the inner solid cylinder. The connection between the main cylinder and the 2 pipes looks odd to me... Don't know why or what key-words I should use to search other problems of the same kind.

At one pipe you can see the problem at the other pipe I improved it a bit but maybe you have better ideas.

[Far]

is this a 3d topology?

[despaired student]

Yes, it's a 3D model

[Far]

plz attach 3d topology files. Did you copy the geometry (processed for 2d blocking) to other end of cylinder?

[Far]

My aim was to mesh the pipes plus the cylinder and the inner solid cylinder.

Right. Do you want to mesh the solid cylinder as well? if so , we can use the Y blocking for this.

The connection between the main cylinder and the 2 pipes looks odd to me

why do you think so? Could you elaborate a bit more?

[despaired student]

Sure, just give me some time and I'll elaborate a bit more.

[Far]

I have also extruded mesh (create block >>>2D to 3D with translate option and Z = -70) and it appears that the problem is related to association.

Didn't find any problem in 2d blocking (improved blocking with minor operations)

[despaired student]

So,

1. I don't know which file is needed for the 3-D topology, so I attach the other files.

2. This cylinder-model is the same model as before but without all the little membrane-cylinders. I thought it would be an easy task to mesh this basic model but even that seems to have some barriers...
For this 3-D blocking I also meshed the solid inner cylinder but it's a good question...do I have to mesh the inner cylinder if it's supposed to be solid and not moved. My task is to simulate the flow from the inlet pipe around the cylinder to the outlet-pipe ...hm, don't know if it's necessary to mesh the inner cylinder?

3. The blocking I described as odd is at the connecting-area of the pipes and the main-cylinder. When I apply Det 2x2x2 or angle quality criterion the program shows me a lot of bad elements piled on this surface - it looks like hundreds of papers piled over one another. That's what I wondered about. You can see it on the attached pictures 1 and 2.

4. Y blocking? I thought of some T-formed blocking to improve the model. Maybe I was on the right track.
When I think about the next steps after the extrusion of the complete 2D-blocking is the next step to connect the outlet- and inlet-pipes to the blocking. First I assumed a normal O-Grid structure for the pipes would be enough but now I doubt that. It is a little bit more problematic or can I just not see the obvious solution?


Best Regards

Sören

[despaired student]

...just read about Y-blocking and watched a video on youtube. This might work, I must try... Do you think it might also work when the 2d blocking is extruded?

[Far]

.

..just read about Y-blocking and watched a video on youtube. This might work, I must try... Do you think it might also work when the 2d blocking is extruded?

Yes. It should work on 3d blocking.

[Far]

1.

I don't know which file is needed for the 3-D topology, so I attach the other files.

The .blk and .tin with 3d blocking and processed geomtry.

2.

This cylinder-model is the same model as before but without all the little membrane-cylinders. I thought it would be an easy task to mesh this basic model but even that seems to have some barriers...
For this 3-D blocking I also meshed the solid inner cylinder but it's a good question...do I have to mesh the inner cylinder if it's supposed to be solid and not moved. My task is to simulate the flow from the inlet pipe around the cylinder to the outlet-pipe ...hm, don't know if it's necessary to mesh the inner cylinder?

If there is no flow in inner cylinder then there is no need to mesh it.


3.

The blocking I described as odd is at the connecting-area of the pipes and the main-cylinder. When I apply Det 2x2x2 or angle quality criterion the program shows me a lot of bad elements piled on this surface - it looks like hundreds of papers piled over one another. That's what I wondered about. You can see it on the attached pictures 1 and 2.

That might be due to association on other end of cylinder.

4.

Y blocking? I thought of some T-formed blocking to improve the model. Maybe I was on the right track.

That is useful when you have three edges and still you want the hexa.
Check this http://www.youtube.com/watch?v=92vScop7b8Q

When I think about the next steps after the extrusion of the complete 2D-blocking is the next step to connect the outlet- and inlet-pipes to the blocking. First I assumed a normal O-Grid structure for the pipes would be enough but now I doubt that. It is a little bit more problematic or can I just not see the obvious solution?

This is very good example similar to your problem
http://www.youtube.com/watch?v=9h97FvWJPcY

This is another good example, not directly related to problem.
http://www.youtube.com/watch?v=KabKF...eature=related

[PSYMN]

As usual lately, I don't have time to open your files... But just from a quick look...

1) to diagnose the problem better, veiw fewer columns of the histogram... Maybe just the first column... Too much on the screen makes it too hard to see the issue.

2) Put a scan plane across the problem area. It will help you understand what about your blocking has squished all those cells against that interface...

3) At the interface between the pipes, is there a surface? If it is open flow, there shouldn't be and the blocking should be continuous without trying to project that between face to anything... If there is a surface, a continuous blocking will ignore it anyway...