Hex mesh for intersections at curves

knarfnitram · September 25, 2025, 7:54am

Hey coreform cubit community,

I have a small question how to create a hex mesh for this stent-like structure:

I created this volume by sweeping a cylinder along this helix curves and uniting 2 curves into to a single volume as displayed in green.
The volume intersects now see here:
intersection

I started by meshing the initial circle and extrude it along the curve, however the sweeped hex mesh of each individual helix is removed during unification of the volumes.

What’s now the best way to mesh this volume with hex elements?

Norbert_Hofbauer · September 26, 2025, 3:20pm

Hi @knarfnitram,
i couldn’t find a good decomposition that doesn’t end up with very skewed elements.
So i got 2 options left if you need hex elements.

The first one is using THex.

#!cubit
reset
create surface circle radius 0.3 xplane 
move surface 1 z 10

sweep surface 1 helix yaxis thread_distance 10 angle 360 right_handed  keep 
sweep surface 1 helix yaxis thread_distance 10 angle 360 left_handed  keep 

delete body 1
unite vol all
compress

composite create surface 1 to 4
Volume 1 scheme tetmesh
volume 1 size auto factor 6
mesh volume 1
thex vol 1

The second one is using sculpt.

#!cubit
reset
create surface circle radius 0.3 xplane 
move surface 1 z 10

sweep surface 1 helix yaxis thread_distance 10 angle 360 right_handed  keep 
sweep surface 1 helix yaxis thread_distance 10 angle 360 left_handed  keep 

delete body 1
unite vol all
compress

sculpt vol all

kgmerkley · September 26, 2025, 3:38pm

A third option would be to introduce cuts around the crosses and specify those regions as tetmeshes. I think you would have to mesh all the swept regions first and then mesh the crosses to create a tetmesh with a pyramid interface. Don’t forget to imprint and merge.

Karl

knarfnitram · September 27, 2025, 7:20am

Hey Norbert and kgmerkley

thanks for your answers and suggestions of thex, sculpt and tetmesh for the junctions.
I tested sculpt and thex - but I’m not quite happy with the mesh quality.

But cutting out the junction seems to be an option, so I’ll take a look if i get meshed the junction with hex.

Best
Martin