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how to get both parts ?

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Old   February 5, 2011, 07:28
Default how to get both parts ?
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Tobias Holzmann
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Hey all together,

i wanna mesh that : picture teg

everytime i mesh it with sHM i got the wrong side : picture wrong - its like i need the negativ from it :/
I solved it but overwrite the case and don' t know how my settings in snappy were :/(


I ve done several settings but don 't get the geometry
if i set the location point into one part of the geometry i just get one of the part not both?

some idea ? it should be possible ... or not ?


Help.
Tobi
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Old   February 5, 2011, 07:55
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Hi Tobi,

OK, now I'm confused... do you want:
  1. The mesh inside both box geometries. This would be a bit odd, since you would need to connect them somehow...
  2. The mesh outside of the boxes.
  3. A mesh that has the outside and the insides of both boxes.
If "b", then just increase the outside mesh box in blockMeshDict and define in snappyHexMeshDict a point closer to the end of this outer box. This way you'll be sure to catch a point outside of the boxes

If "a" or "c", see the tutorial "heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeater", since you'll be dealing with multiple mesh regions, each one requiring a well defined way of exchanging physical values...

By the way, be sure that the STL geometries don't have any leaks. AdMesh can help with that.

Best regards,
Bruno
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Old   February 5, 2011, 09:16
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hi bruno hope i can clear your confusion.

first i am using chtMulti - so i need several parts of regions.
I had a look at the tutorials and its all clear if i have to mesh "one" geometry. : picture


its just a little extract. Okay so far ...

In the middle i have the parts i wanna mesh.
The STL file includes all boundary conditions.

Don 't know how i should explain it. ... hmm.
Okay if i mesh one part its no problem.

But in the middle i have 2 or 3 or 4 or 10 parts of the same behavior . So i wanna mesh all parts of the same behavior to get one region for all those parts in the middle.

Is it clearer now ?

Tobi
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Old   February 5, 2011, 13:17
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Hi Tobi,

Mmm, I'm still having trouble understanding you Possibly it's because I'm tired from the week, so my brain is very slow today

OK, as far as I can understand, you have two unconnected blocks in a single STL. And you want to generate a mesh inside them and outside them, correct?

Well, my experience with multiple regions is limited, but I think that you'll need to resort the same scheme as the tutorial case "snappyMultiRegionHeater". In other words:
  1. you must have 1 STL file for each box;
  2. you must have additional STL files/boxes for the volume you want to use for interfacing with those two boxes.
Only then will you be able to properly defined the regions outlined by your geometries! Otherwise, if there isn't any connection between those boxes, sHM will very likely ignore one of them, because sHM was designed for creating a single contiguous volume.

When it comes to separating the mesh into various regions, splitMeshRegions is used, according to the faceZones/cellZones identified in snappyHexMeshDict.

The working sequence is outlined in Allrun in "snappyMultiRegionHeater".

Best regards,
Bruno
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Old   February 5, 2011, 14:11
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Hi

first - thanks a lot.

Ehh i just wanna hava a mesh inside both parts.
Meshing every region part sperate not in a whole STL like the heatTransfer snappy tutorial, couse if i do that i got "for example" for the parts in the middle

30 different parts.

first is correct -> name region = teg
second ... domain1 . domain2 ...

but its okay. I think i can 't do that.
Thanks for your help. My english skills are not as good as it should to give an implicit notice what i wanna do.

A nice weekend.
Tobi
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Old   February 16, 2011, 07:22
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Okay - its not possible to get all regions in one step. I 've split it to several domains like you said and now it works


Now i know how to do it.
thx Tobi
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Old   February 17, 2011, 17:14
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Hi Tobi!

I'm glad you've finally got the handle on this meshing issue
You might consider useful to learn a bit of bash scripting and how to use sed and grep, in order to make the whole procedure faster to do and use

Best regards,
Bruno
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Old   January 9, 2012, 06:32
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Quote:
Originally Posted by Tobi View Post
Okay - its not possible to get all regions in one step. I 've split it to several domains like you said and now it works


Now i know how to do it.
thx Tobi
Hello Tobi,

I have been struggling with the multiRegion SHM for a long time. I have two stl files: iblock.stl and oblock.stl. They are two cubes next to each other. I want to create mesh inside both the two cubes. But the mesh is always not correct.
such as :

Cellzones:
iblock size: 38975
oblock size:0

Could you please, if possible, send me your case?

Thank you so much!
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Old   January 9, 2012, 09:01
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Quote:
Originally Posted by aqua View Post
Hello Tobi,
Cellzones:
iblock size: 38975
oblock size:0

Could you please, if possible, send me your case?

Thank you so much!
Hi Aqua,

i think you have the same problem like I had a time ago.
Are your Meshparts connected? If not you have the same problem.

My chtMulti Case is no more avaiable :/ sorry.
But maybe in my backup. I 'll have a look at my hard disk today evening, hoping to find it and send it to you.

Tobi
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Old   January 9, 2012, 10:09
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Quote:
Originally Posted by Tobi View Post
Hi Aqua,

i think you have the same problem like I had a time ago.
Are your Meshparts connected? If not you have the same problem.

My chtMulti Case is no more avaiable :/ sorry.
But maybe in my backup. I 'll have a look at my hard disk today evening, hoping to find it and send it to you.

Tobi
Hi Tobi,
thank you so much for your help!
my problem is, after running snappyHexMesh, only the file "iblock" has the file "polyMesh" which contains the iblock mesh. But in the file "oblock", there is no such a file named "polyMesh"......

Thank you again!

Aqua
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