Welcome @pmaurerl!

The reason is that the `sweep`

mesh scheme can only be swept “from a single surface, to another single surface” *or* “from multiple surfaces, to a single surface”. It is not possible to sweep (in Coreform Cubit/Trelis) from one surface to multiple surfaces.

A surface-meshing scheme that you might be interested in exploring is the `triprimitive`

scheme. While that might sound like a triangular mesh generator, it actually meshes a topological triangle with quads and produces meshes quite similar to the `circle`

mesh scheme if the surface is a quadrant of a circle.

Another scheme you may be interested in is the `polyhedron`

scheme which is similar to `triprimitive`

but tends to place the extraordinary point (valence-3 node) closer to the center of the quadrant. Below is a comparison of these three schemes.

(L-R)

`triprimitive`

,

`polyhedron`

,

`circle`

However these schemes don’t provide as much control over the mesh layout as `circle`

.

An alternative approach, that is more difficult to manage, is to use your initial approach, but not assign those elements to a block:

```
reset
cylinder radius 1 height 4
webcut volume all with plane zplane offset 1.5
webcut volume all with plane zplane offset 1
imprint all
merge all
surface 3 scheme circle
mesh surface 3
mesh vol all
block 1 vol 1 3
block 1 hex in vol 2 with x_coord<0
draw block 1
```

But notice that because there wasn’t any geometry to constrain the layout of the hex-mesh, that the cutout region isn’t flat. Thus my recommendation is to webcut the cylinder into quadrants and then use the `triprimitive`

or `polyhedron`

mesh scheme as discussed above.