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-   -   [snappyHexMesh] multiple regions (https://www.cfd-online.com/Forums/openfoam-meshing/112637-multiple-regions.html)

Haces April 4, 2013 07:29

O really?? Thanks!!

I will work with it!!

billie April 23, 2013 06:40

Quote:

Originally Posted by Tobi (Post 409560)
Okay now it's gonna be a monolog :)
1. Download Link activated above.
http://www.holzmann-cfd.de/index.php...waermetauscher
Tobi

The link on the page mentioned above currently does not work. Is it possible to make the file "abgaswaermetauscher.tar.gz" available for download again.

Thanks in advance.

Tobi April 23, 2013 12:14

Quote:

Originally Posted by billie (Post 422541)
The link on the page mentioned above currently does not work. Is it possible to make the file "abgaswaermetauscher.tar.gz" available for download again.

Thanks in advance.

Thanks for reporting the wrong link :)
Working again!

billie April 23, 2013 13:32

Quote:

Originally Posted by Tobi (Post 422659)
Thanks for reporting the wrong link :)
Working again!

Thanks a lot. I am especially interested in the case because I want to see you handle the boundary creation for the multi-region case.

I tried to mesh a multi-region case but the boundaries/solids from the stl files are not preserved for multi-region cases by sHM.

woodwick August 8, 2013 19:54

Tobi,

I would like to download abgaswaermetauscher.tar.gz but the link you gave before doesn't work. Can you share it again?

Thanks

wyldckat August 16, 2013 19:08

Greetings to all!

@Alessandro: Tobi once in a while renovates his website :)
Check his current tutorials for snappyHexMesh: http://www.holzmann-cfd.de/index.php/tutorials - with any luck, he made a variant of the tutorial that is missing...

Best regards,
Bruno

lramutti May 4, 2014 00:37

Hey Tobi,

I am going through a similar problem at the moment and I tried to access your website but it seems that the case is no longer available. Would it be possible for you to uploaded it again?

Cheers

Lucas

Tobi September 9, 2014 09:36

Hi all,

I did not regenerate the old case but created one new.
Its cheaper (computational time) and I think its easy to get the point.

You can check it out here:
http://www.holzmann-cfd.de/index.php...ppymultiregion

A better choice is to get to that page (maybe some link will changed in future :D)
http://www.holzmann-cfd.de/index.php/en/tutorials-en

bbita July 27, 2017 11:49

Hi Tobi,

I am not sure if this thread is still active. I am trying to model a porous media with several disconnected grains. I used snappyHexMesh and splitMeshRegions. I am not sure, if I can define all those grains as one region.

Thanks,

Tobi July 27, 2017 12:06

Hi,

active or not active I will get an notification :)

- You want to make a cht case? Yes you can specify each of the grains as region but I think there are better ways.
- Giving more information about what you are trying to do would be much better and we could give more tips

bbita July 27, 2017 12:14

Hi Tobi,

At this stage, I want to use cht, but later I want to combine cht with interfoam (I hope I can do that :D:D). If I can have only two regions (grain and fluid), it makes my model easier for the next steps.

Thanks

JoeFriend February 16, 2018 16:23

Hello Tobi,

I'm having a similar problem you had once: when using splitMeshRegions after SHM, I get multiple extra domains with one or two cells between my regions. Some of the things I've done to try to solve this:
- verifying my STL files are closed (I used SALOME to create them and then surfaceCheck in OF)
- use different parameters in SHM dictionary (the more I refine the mesh and the edges, the more cells I get between my regions)
- I followed your suggestions (posts #28-31) of having separated STL files for each region, with a different name for each patch.
- I've checked the setup of other SHM cases with multiple regions (tutorials in your web site, OF tutorials, etc)

but the problem is still there...I have run out of ideas by now :(
Considering I've tested similar configurations than other cases, I think the problem could be related to my STL files, but I don't see where. I would really appreciate any suggestion :)

A simplified version of my case can be found here
https://drive.google.com/open?id=1Fs...uus3SSEuR4nCm4

Best regards,

Jose Amigo

bbita March 17, 2019 13:05

1 Attachment(s)
Hello All,

I have a similar problem. The stl files are attached. I would like to have two regions; one fluid which is the cube itself and one solid which consists of two unconnected spheres. However what I am getting from snappyHexMesh is Flow, domain1, and domain2. I appreciate your help. Thanks

bbita March 23, 2019 12:34

Dear Foamers,

I found the solution (might not be the best but works :D).
I used two different stls for each spheres. So in total I have flow, sphere1, and sphere2. after I SHM the stls, I changed cellZones and faceZones manually by moving the points of sphere1 and sphere2 to one region.

I hope it can help someone.

Thanks

leogermer June 12, 2019 11:41

2 Attachment(s)
I have a case which is a heat exchanger with a fluid phase and a solid phase (consist of plate and all the fins disposed along the plate)

One STL for the fluid phase containing inlet,outlet and the patches through the plate and the channels

And another STL for the solid phase containing the fins, both ends of the fins (which i want to add some extra refinement), and the plate itself.

Now i tried:

1. Generate the STL's using Freecad (see attachment)
2. Merging the regions with command cat main.stl inlet.stl ... > fluid.stl
3. Generate background mesh with blockMesh
4. Meshing with sHM, creating a cellZone for the fluid and solid
5. Split the mesh creating only one extra domain which would be what is left from the background.
6. Set up the boundaries and solve with chtMultiRegionSimpleFoam


What i'm getting:

1. Sometimes it cuts one of the fins on the castellated step of sHM;

2. 99 more domains when execute splitMeshRegions -cellZones. i investigated where those domains were and it was near the interfaces of the fins and the fluid phase.

I tried to follow what Tobi got and downloaded his tutorial case 'snappyHexMeshcellZoneMeshing', but i don't know how i can manage to put boundaries at the fluid region, since in this tutorial you don't actually have a cellZone for the fluid phase.

fpreiss October 7, 2019 13:05

4 Attachment(s)
Hello, I stumbled into the same issue as the others in this thread and think I found a more practical solution than what was shown before. As the link to abgaswaermetauscher.tar.gz did not work for me, I attached a similar and simple testcase based on the multiRegionHeater tutorial with the meshing unrelated files removed. The case files should work on both OpenFoam6 and OpenFoam7 (OpenFoam4 would require adjustments).
I found that of the two disconnected regions in inner_boxes.stl only one would show up in paraview when looking at the reconstructed case - however in the decomposed view it was displaying both albeit as two separated regions (inner_boxes & region1).


Changing the line

Code:

runParallel splitMeshRegions -cellZones -overwrite
to
Code:

runParallel splitMeshRegions -cellZonesOnly -overwrite
in Allrun did the trick for me.

FrancescaMangani March 29, 2020 04:53

Too many regions with splitMeshRegions
 
Quote:

Originally Posted by Tobi (Post 407645)
Hi Bruno,

I have an idea and I think its working but now I have a strange problem. With checkMesh I get 4 regions but if I split my mesh into my regions I get over 70 regions - most of them just contain 1 - 3 cells.

How can I provide that problem?

Code:

Region    Cells
------    -----
0    57621
1    12473
2    59994
3    201142
4    2
5    3
6    1
7    1
8    1
9    1
10    2
11    2
12    3
13    1
14    2
15    4
16    1
17    2
18    3
19    1
20    3
21    2
22    1
23    1
24    2
25    1
26    1
27    19
28    2
29    15
30    2
31    2
32    2
33    1
34    1
35    2
36    1
37    2
38    1
39    1
40    1
41    2
42    4
43    2
44    2
45    3
46    1
47    2
48    3
49    1
50    3
51    1
52    1
53    1
54    2
55    1
56    1
57    2
58    1
59    1
60    2
61    1
62    1
63    1
64    1
65    2
66    2
67    1
68    1
69    1
70    1
71    1
72    2
73    1
74    2
75    1
76    1
77    1
78    1
79    1





Hi Tobi,


did you manage to solve the problem eventually??


I have to use splitMeshRegions with a very complex geometry and I find many regions with splitMeshRegions... I solved the problem in some zones, where I found defects in the stl file, but I still have too many regions, and I don't understand what is the main reason for this behaviour of splitMeshRegions.


I really hope you can help me because I have no more ideas... :(


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