Difficulty meshing a Dome Volume

Hello!

I am trying to mesh a Volume consisting of a dome, and I’m having some trouble. This could be due to the way I am making it, but I am able to mesh the surfaces of the dome just fine, so I’m not sure why the volume would have trouble meshing. Anyways, here’s what I would like to mesh:

As a shared surface between the dome and cylinder, I figure meshing the top of the cylinder first is a good idea:

surface 9 size 0.2
mesh surface 9

With this defined, I figure I should be able to mesh the dome and cylinder, but when I try I get this in the command window:

Cubit>mesh volume 3
WARNING: Volume 3 must have its meshing scheme explicitly specified;
it is not automatically mappable, submappable or sweepable.
ERROR: 1 volume(s) did not mesh :  3

Cubit>mesh volume 1
WARNING: Volume 1 must have its meshing scheme explicitly specified;
it is not automatically mappable, submappable or sweepable.
ERROR: 1 volume(s) did not mesh :  1

Using a tetMesh scheme will mesh the volume, but my model requires quad elements.

I am able to mesh surfaces just fine:

mesh surface 11
mesh surface 12
mesh surface 13
mesh surface 14
mesh surface 15

(See uploaded photos in replies)

Even the inside will work:

mesh surface 20
mesh surface 19
mesh surface 18
mesh surface 17
mesh surface 16

(See second uploaded photo in replies)

But even after meshing all surfaces, the volume mesh is not able to be resolved. I can see why the top inside and top outside central surfaces may have trouble due to differences in the path meshes, but even leaving one of these unmeshed does not allow it to mesh. Any help would be much appreciated.

As a new user, my post could only contain one uploaded photo. Here’s a picture of the outside surface meshed:

And here is a picture with the inside surface and shared surface meshed

I also figure that giving some context into how the geometry for this dome was created may be crucial information. Basically, I started by creating a surface of the cross section of the dome by first defining specific vertex positions.

create vertex 1.0 0 0.75
...
create vertex 0.98 0 0.75

then I created curves from these vertices to trace the surface:

create curve arc three vertex 7 8 9
...
create curve vertex 17 18
...

I then defined a surface by bounding with the curves, swept the surface about the z axis, and imprinted and merged the new volume with the cylinder

create surface curve 7 8 9 10 11 12 13 14 15 16 17 18
sweep surface 10  zaxis angle 360
imprint volume 1 3
merge volume 1 3

Anyways, I hope this helps!

Well, I thought I found a resource that had the solution to my problem, but no such luck. Purely by chance, I stumbled upon this tutorial (https://www.youtube.com/watch?v=Uk5XN5K-srE) for meshing a partial sphere on the Coreform site. I figured that even though it wasn’t the exact problem I was trying to solve, it shared the curving characteristics. Since I thought that the problem was the inner cylindrical part having curvature, I set the four innermost nodes to a rectangular shape that I trace to make the surface to sweep to make the dome.

...
create vertex 0.1 0 1.269
create vertex 0 0 1.269 # Real point is 1.27
create vertex 0 0 1.211 # Real point is 1.213
create vertex 0.1 0 1.211
...

Next, I tried recreating the steps from the video within my geometry, and was able to at least get the shared surface and most of the outer and inner portions of the dome meshed. However I still am having problems meshing the inner cylindrical portion.

ERROR: 1 volume(s) did not mesh :  5

It doesn’t even say anything about it not being a sweepable volume anymore, just the cryptic message above. Can anybody provide some insight here?

Alright, I figured it out. The problem seems to be with generating the circular part on top from the sweep that defines the dome volume. Basically, I just stopped at generating vertices at the point just before the ones at the x, y origin, swept the dome volume creating a dome with a circular opening at the top, generated a new separate cylinder to fit into that hole and moved it there, and then webcut the dome volume in half and was able to mesh everything.

1 Like

@jbtompkins,

Based on what I can see from your post, I believe the issue you’re facing is that Cubit doesn’t support Many-to-Many sweeps (but does support One-to-One, Many-to-One, and One-to-Many). One way to get this to mesh, without needing to webcut the dome, is to composite the surfaces of one of the dome’s sides into a single surface.

reset
graphics tolerance angle 15

## Create half dome geometry with curves on half-dome
sphere r 1
sphere r .9
subtract vol 2 from vol 1
webcut volume all with plane yplane 
delete vol 3
compress

surface all copy
delete vol 1

webcut body all with cylinder radius .85 axis y 
webcut body all with cylinder radius .75 axis y 
webcut body all with cylinder radius .6 axis y 
webcut body all with cylinder radius .4 axis y 
webcut body all with cylinder radius .2 axis y 

color curve all black
create volume surface all heal 
graphics tolerance angle 1

## Composite all the surfaces on the dome-top into a single surface
composite create surface 9 13 17 21 25 26 keep angle 15 

## Mesh the geometry
surface 24  scheme circle 
mesh surface 24 
surface 23 19 15 11 7 scheme pave
paver cleanup extend
surface 23 19 15 11 7 scheme pave
surface 23 19 15 11 7 scheme pave
mesh surface 23 19 15 11 7
volume 14  redistribute nodes off 
volume 14  scheme Sweep  source surface 24 23 19 15 11 7    target surface 27   sweep transform least squares 
volume 14  autosmooth target on  fixed imprints off  smart smooth off 
mesh volume 14 

Before

After

Meshed

1 Like

Not sure if I should open a separate thread, but this problem seems related, so I figure I’ll post it here for now. I am now able to mesh the dome and the cylindrical section; however, I need to add a second dome to the other open side of the cylinder. I am able to add the geometry for the second dome and mesh it, but when I do, the mesh on the cylinder is removed (as far as I can tell).

I do not appear to have any error messages pop up when meshing the second dome, but when I try to mesh the cylinder’s volume, I get this error message:

Command: mesh volume 104
ERROR: 0 three-faced corner nodes found.
ERROR: A logical cube was not able to be found.
ERROR: Volume 104 meshing unsuccessful using scheme: submap
ERROR: 1 volume(s) did not mesh :  104

I thought I was home free once the domes were meshed, but the cylinder is now giving me this trouble…