Error with hex mesh of partition (two flat sheets on top of each other)

Hello,

I am trying to create a hex mesh on a partition of two flat sheets -- for example, one 200 x 200 x 10 and another 50 x 50 x 1.

I create Box1 and Box2 for the two films, respectively, and then I create Partition 1 out of Box 1 and 2. Then I do meshing and choose an option of 3D Hex. The meshing, however, fails and shows this error message: "Unexpected geometry. Wrong number of wires: 2"

On the other hand, if I set the lateral dimension of two sheets the same, I do not get this error. Also, if I use other free volume meshing like Netgen meshing, I do not get any error message, and the meshes between the two Boxes are nicely connected. From this, I can make a crude guess that the error comes from the two faces from each Box that make contact clashing during hex meshing.

I cannot use non-hex mesh, because my goal is to simulate very flat sheets (for example, 2mm x 2mm x 50nm sheet), and other meshes fail due to this very high anisotropy.

This is a very simple geometry meshing, but I've been quite struggling and am not able to come up with any answer. I would greatly appreciate any suggestion.

Hello

"Unexpected geometry. Wrong number of wires: 2" means that some face is not a quadrilateral as Hexa meshing requires. I suspect that the faces at the interface between the two boxes are not equal enough. To fix it, try to increase tolerance of the boxes using Limit tolerance before Partition them.

Best regards

Edward