Discussion Forum

Hi

I suspect either you have not turned ON the interiour boundaries (check box lower left of your Boundery Settings window).

Or its the dxf, as DXF is not the best protocol, polylines are not always defined correctly depending on the software you use, a line can be an assembly of very small segments with gaps in between and this COMSOL would have some difficulties to understand as it wants closed lines and linked segments, to within its "repair" or import tolerances.

Check out the documents under "repair" import option tolerance and have a carefull look at your geometry.

I would suggest that you use COMSOL for 2D geometry its rather nice and easy.

Good luck
Ivar

Hi Ivar

Hi Ivar

I have turned on the interior boundaries, but all of the boundary section numbers and the group box are inactive, so that i can not change and regroup the boundaries.

Actually I can't make the COMSOL understand that my environment is a subdomain with two holes inside (jpg file attached). So when it starts meshing it just segments the lines!! and not the area between the closed loops. It's stupid.

I had a very carefull look on the geometery and it seems to be solid enough and has no problem. Actually I couldn't find any software for transforming jpg to .mphbin or .mphtxt , but it seems that the problem is something else

Thanks anyway for your kind help
Regards
Ali

Hi again,

I almost could resolve it, although I don't know exactly how. Since the documents are not very descriptive and I haven't passed a course on COMSOL.

It was handled by using:
"Split Object" , "Creat Composite Object" , "Coerce to Curve & Solid", ...

although I don't know what exactly has happened and how it worked, but I could finally define the environment.

Good teaching lecture notes on COMSOL for understanding the COMSOL basics would be appreciated.
I have read the user guides and other COMSOL docs, but seems not to be enough

Thanks
Ali

Hi,

This is common practice when importing DXF files, which often contains the boundaries (edges) of the domain but no information about the solid domains that they enclose. You therefore need to form solids during or after the import before you can use the geometry for analysis (unless it represents a truss, for example). You can do so in two different ways:

- In the Import CAD Data From File dialog box, click "Options" before importing the DXF file. In the CAD Import Options dialog box, click the "Try forming solids" button and then click "OK".

- After the import, with all boundaries (curve objects) selected, click the "Coerce to Solid" button on the Draw toolbar.

In both cases there may be solid domains that, for example, are air domains that will not be part of the computation. You can then click the "Split" button on the Draw toolbar to split large composite solid objects into individual geometry objects for each enclosed subdomain. That makes it possible to delete them or use other CAD tools in COMSOL Multiphysics to further modify the geometry for the finite element analysis.

Best regards,

Magnus Ringh
COMSOL AB

Hi Magnus

Thanks a lot for your helpful comments

Regards
Ali