Meshing a perfectly circular annulus

[Brennen Carr]

Hello,

I have been trying to mesh a perfectly circular annulus. I created the model using an external CAD software and then imported the model into simvacular. I found a prior thread that stated I should follow regular meshing procedure, however I have encountered 2 errors in doing this:

1. I get an intersection of segments at a point inside the inner radius of the annulus, where there is/should be no model. normally this is in the same plane as an endcap.
2. I get an error message stating that there are "too many regions here"

I have been able to turn on "fast-meshing" and mesh my model but I wanted to use the boundary layer meshing feature to refine the mesh along the inner wall.

Thanks for your help!

Brennen Carr

[David Parker]

Hi Brennen,

The first error may be due to a failure to import the CAD file correctly. Are you importing using NURB surfaces or polygonal surfaces (STL)?

The second error is most likely caused from trying to mesh a geometry that is not connected (i.e. no shared vertices).

Could you post your CAD model here? I will have a look to see what the problem is. If the file is too large to post here then please open a GitHub issue and upload it there.

Cheers,
Dave

[Brennen Carr]

Hello Dave,

I am using an STL file exported from an online CAD software called onshape, ive attached the model.

I have imported external models (stl formatting) to simvascular before with no issues, but is the NURB formatting better suited for this?

Sincerely,

Brennen Carr

[David Parker]

Hi Brennen,

Exporting a model using NURB format is preferable, retains the intrinsic values of the geometry (e.g. curvature) and face boundaries, whereas STL just samples these. I've also seen some pretty bad STL files, very long triangles that cause meshing problems. The STL file you uploaded has 14K triangles and would probably make modeling more difficult and error prone.

Try importing a NURB format file instead of STL. I bet that will work OK.

Cheers,
Dave