Meshing organic component

Coreform Cubit
#1

Coreform Cubit Version: 2021.11
Platform: Windowd 10 Pro

Issue
New to meshing I’m trying to tet mesh this liver model so to generate a fine 40k tets volume, seems every time I’m trying some approach there is a problem I’m not able to overcome, so wanted to ask for some hint.
I have generated also this stl version of the shape filled with tet using Houdini Tet Embed node, seems is impossible to open it in Cubit but is opened in Gmsh telling there is no tet inside.

#2

Welcome to the Coreform Cubit forum!

The issue with this model is that it does not form a closed set of triangles. Cubit is not the best tool out there so solve this problem, but in this case, I can get it to work. Remember tetrahedra are normally created on a closed volume. In your case, I will create a closed set of triangles, and tetmesh those.

My comments are in the journal file below.

reset
import asset "~/Downloads/liver3-HD.obj" tolerance .001 make geometry on
create volume surface all noheal
# There are a couple of sliver surfaces that will create bad elements.
# Get rid of them. 
composite create surface all
# I just wanted to see the surface mesh first.
surface 7 scheme trimesh
mesh surf 7
vol 4 scheme tetmesh
mesh volume 4
list totals

This creates ~57K tets.

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image769×503 43.9 KB

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image771×512 57.7 KB

1 Like
#3

Thanks a lot this is great.
A few more questions I’m a bit ashamed to ask:

  • clipping the resulting mesh seems to show only the surface and not the tet
    image
    even if exporting as bdf and visualizing in another program the internal structures are there
    image
    image728×507 54 KB

    any way to enable the kind of visualization you have shown
  • 57k it’s too much for my test and for my free license (so far testing on realtime sim system on CPU before switching to GPU, so 40k will be already too much), there is any way to impose or drive a lower number of generated tet, around the 40k I have written before
#4

Drawing volumetric elements

By default we don’t draw volumetric elements for rendering performance. However, you can use the draw command to force elements to be drawn. For example:

reset
sphere r 1
vol 1 scheme tetmesh
mesh vol 1

graphics clip on

draw tet all

image
image594×583 32.4 KB

Regarding the element count limit.

You have a couple options here.

  1. You can sign-up for a 30-day trial license, which has no element export limit. You can do this by logging into your Coreform account and then clicking on the link in your account portal:

    image
    image1149×487 24.9 KB

  2. You can modify the mesh size to attempt to create fewer elements. You can do this by modifying the surface and volume meshing parameters within the tetmesh scheme (larger angles, larger gradations, larger min size, etc):
    image
    Or by setting a larger size in the intervals dialog:
    image
    The current mesh size is listed in the Properties Page if you first select the volume you want to query:
    image
    which can give you a good idea for what value to put into the Approximate Size box in the previous image.

1 Like
#5

Thanks, I was able to get 39.7k tet using the Auto Factor slider
image