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Old 28th November 2017, 01:43 AM   #11
DonVK is offline DonVK  Canada
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Yes, that was cryptic now that I read it again. It was clear to me when I wrote it . That said, I'm not an expert on 3D mesh or gmsh.

Your original mesh file only has element type "2" =triangles, with 2 tags, and the expected 3 nodes and it was used exclusively. This is unusual, as there are no points (type=15, 1 node) or lines (type=1, 2 nodes). These other element types have different number of fields, so the number of columns will change. That's why I used a spreadsheet, I can import them using comma or space to separate the fields to make it easier to view this information. Hopefully that's clearer this time round. When I regenerated the mesh from step, I see element types of points, lines and triangles and ABEC is happy again. I attached the gmsh2 file spec so you can have a look.

I can't pinpoint specifics of a node or element causing the error. it may have been an open surface or an overlap. The ABEC error was occurring in both the inner and outer box, it was flagged and ABEC died on the outer box just because it was listed first in the file.
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File Type: pdf msh_20.pdf (48.6 KB, 17 views)

Last edited by DonVK; 28th November 2017 at 01:46 AM. Reason: added gmsh spec
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Old 28th November 2017, 01:52 AM   #12
Patrick Bateman is offline Patrick Bateman  United States
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Have you read Gaga's post on the German forum? I translated them into English and they helped me a lot. ABEC is still an exceptionally difficult program to learn though.
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Old 28th November 2017, 02:00 AM   #13
DonVK is offline DonVK  Canada
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Do you mean the ones on DIY-HIFI-Forum - Powered by vBulletin ?
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Old 28th November 2017, 02:11 AM   #14
Patrick Bateman is offline Patrick Bateman  United States
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Yes. This thread by Gaga:

Der ABEC Thread... - DIY-HIFI-Forum
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Old 28th November 2017, 08:49 AM   #15
Gaga is offline Gaga  Europe
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Hi,

The meshing step, i.e. quality of the mesh is indeed critical for ABEC simulations.

From the thread mentioned by Patrick Batemen a stepwise description how to move from a CAD-file (STEP-file) to gmesh and to ABEC:
- Get a step-file from a CAD program, post #248.
- Get a mesh-file in gmesh, post #250.
- Import the mesh to ABEC, post #252.

There are some hints on favorable settings in gmesh in other posts, e.g. set element size (fineness of the mesh) in gmesh exclusively via 'Element Size Factor' or activate 'optimise hexa netgen' for meshing.

I can summarize my preferred settings here if interested (not necessarily the best for all applications though, but may be a good start).

Christoph
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Old 28th November 2017, 11:20 AM   #16
natehansen66 is offline natehansen66  United States
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Don - I'll take a look at what you're talking about later.

Quote:
Originally Posted by Patrick Bateman View Post
Have you read Gaga's post on the German forum? I translated them into English and they helped me a lot. ABEC is still an exceptionally difficult program to learn though.
Yep! Found that a couple years ago and it has been a huge help. I've been going back through it a ton lately. Google translate works fine.

Quote:
Originally Posted by Gaga View Post

I can summarize my preferred settings here if interested (not necessarily the best for all applications though, but may be a good start).

Christoph
I'd appreciate that.
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Old 28th November 2017, 08:31 PM   #17
Gaga is offline Gaga  Europe
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Hi,

Just ask if something gets messed up with google translate in the ABEC thread - I'm happy to translate the respective parts.

Will summarize my preferred gmesh-settings here these days as well. Just busy right now...

Christoph
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Old 29th November 2017, 07:12 PM   #18
Gaga is offline Gaga  Europe
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OK, here is how I actually use Gmsh.

Disclaimer 1: I'm using version 3.0.4 for OSX, other versions might look a bit different.
Disclaimer 2: This may not be the best option to mesh for all situations. I just works fine for me.
Disclaimer 3: You probably know most of the steps. I explain in some detail anyway in order to make it clearer for ABEC beginners....

Here we go.

The respective *.step-file has been opened in Gmsh.

I then apply following settings choosing 'Tools' and 'Options'.

Options 1
Within the 'Options' Window I choose 'Mesh' - 'General' and
- 'MeshAdapt' as 2D algorithm:
ABEC experts - help!-2017-11-28-gmesh-options-1-png
Moreover I define the mesh-resolution here by giving a number for the 'Element size factor'. The lower the number, the higher the resolution of the mesh.

Options 2
Before meshing, I select 'Optimize quality of tetrahedra with Netgen' under 'Tools' - 'Options' - 'Mesh' - 'Advanced':
ABEC experts - help!-2017-11-28-gmesh-options-2-png

Mesh
ABEC experts - help!-2017-11-29-gmsh-2d-mesh-png
I do meshing via 'Mesh' - '2D'

Surface numbers
Surfaces labels can be seen choosing 'Surface labels' under 'Options' - 'Geometry' - 'Visibility'
ABEC experts - help!-2017-11-28-gmesh-surface-labels-png
You'll need these numbers in the 'Elements' Script in ABEC in order to reference the respective surfaces.

Save mesh:
ABEC experts - help!-2017-11-28-gmesh-save-mesh-png
Not much to comment here. The mesh file can then be imported to ABEC. The size of the 'XY.mesh' file gives a good indication on how long your computer will need to solve the file in ABEC.

Hope this helps.

Christoph
Attached Images
File Type: png 2017-11-28 GMESH Options 1.png (203.3 KB, 442 views)
File Type: png 2017-11-28 GMESH Options 2.png (188.3 KB, 442 views)
File Type: png 2017-11-28 GMESH surface labels.png (369.4 KB, 389 views)
File Type: png 2017-11-28 GMESH save mesh.png (631.5 KB, 390 views)
File Type: png 2017-11-29 GMSH 2D Mesh.png (194.6 KB, 446 views)
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Old 29th November 2017, 10:07 PM   #19
natehansen66 is offline natehansen66  United States
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Christoph - that helps a ton thanks! I've been flying pretty blind in Gmesh with only some very basic guidelines from the German forum and I probably misinterpreted something along the way

I just re-meshed my drawing with your suggestions and ABEC solved no problem.
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Old 30th November 2017, 08:47 PM   #20
Gaga is offline Gaga  Europe
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Happy to hear the description worked for you!

The posts on the use of Gmsh in the 'ABEC Thread' are indeed a bit confusing/messy. May be I should summarize the information on Gmsh in a new posting over there as well occasionally...
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