Freecad 2D brep files failed to show up in gmsh (solved)

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Gary R
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Joined: Thu May 28, 2015 10:59 pm

Freecad 2D brep files failed to show up in gmsh (solved)

Post by Gary R »

I have been trying to model the flow in a piping system. I created a sketch in freecad and have tried several approaches to creating a 2D surface and then exporting the results as a .brep file to gmsh. The files do not show up on the gmsh GUI. I have tried to use the surface workbench and the part workbench to create a surface. Neither seem to work. Attached is the freecad file for the project.

Thanks for you reply
Gary R
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PointContact.FCStd
(14.02 KiB) Downloaded 27 times
Last edited by Gary R on Tue Jan 18, 2022 6:05 pm, edited 1 time in total.
chrisb
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Re: Freecad 2D brep files failed to show up in gmsh

Post by chrisb »

I'm not at all sure about this, but doesn't it need something 3dimensional to model airflow?
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KAKM
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Re: Freecad 2D brep files failed to show up in gmsh

Post by KAKM »

chrisb wrote: Mon Jan 17, 2022 11:05 pm I'm not at all sure about this, but doesn't it need something 3dimensional to model airflow?
It depends on what you're trying to model. You don't need a 3D model unless you're trying to capture a 3D phenomena (e.g., turbulence). It's pretty common to use a two-dimensional model to get a general sense of what the system is doing (pressures, velocities, etc.) since it computes so much faster, and then go to three dimensions as needed for additional information.
chrisb
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Re: Freecad 2D brep files failed to show up in gmsh

Post by chrisb »

Thanks for the info! Should I move this to the FEM forum?
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Gary R
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Re: Freecad 2D brep files failed to show up in gmsh

Post by Gary R »

KAKM is correct . I use 2D for all kinds of symmetric models but have a chronic problem of things not showing up in gmsh. I know that I am doing something fundamentally wrong but what?
Gary R
KAKM
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Re: Freecad 2D brep files failed to show up in gmsh

Post by KAKM »

Figured it out. I think you had the body selected when you clicked export–that yields an empty file. If you select the three surfaces of interest, then click export, the resultant file is (I think) what you wanted. It opened in gmsh just fine for me.
chrisb wrote: Mon Jan 17, 2022 11:46 pm Should I move this to the FEM forum?
It might be easier to find there for someone with a similar question later. Or it might not be.
user1234
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Re: Freecad 2D brep files failed to show up in gmsh

Post by user1234 »

Important for that are the FreeCAD infos (see red banner above), the VTK version and the report output.

Just said: atm FEM with gnsh have issues with VTK > 7 .

Greetings
user1234

edit: minor typo
chrisb
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Re: Freecad 2D brep files failed to show up in gmsh

Post by chrisb »

Moved.
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Gary R
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Re: Freecad 2D brep files failed to show up in gmsh {solved}

Post by Gary R »

My sketch essentially contains 3 parts. If I use the surface workbench on each part separately and then highlite all 3 surfaces to export, gmsh works fine.
I included the new file.

Gary R
Attachments
PointContact.FCStd
(13.54 KiB) Downloaded 20 times
user1234
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Re: Freecad 2D brep files failed to show up in gmsh (solved)

Post by user1234 »

So, now i can test files. For me all files meshes fine. But i get on the newer file errors in the sketch. This is probably because you use an older (or other) version of FreeCAD (i do not know, since i have no infos). But as long it works for you.

testet with:

Code: Select all

OS: Debian GNU/Linux 11 (bullseye) (X-Cinnamon/lightdm-xsession)
Word size of FreeCAD: 64-bit
Version: 0.20.27089 (Git)
Build type: Release
Branch: master
Hash: ead1bce8e994358388fd6dd993f0c9b756ec0eac
Python version: 3.9.2
Qt version: 5.15.2
Coin version: 4.0.0
OCC version: 7.6.0
Locale: English/United States (en_US)
with:
gmsh 4.9.0
VTK 7.1.1


Greetings
user1234
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