[Hershey]

How would one treat the inner cylinders' wall thickness. I am not interested in their properties, just the flow around them. Do I still have to mesh the walls?

[-mAx-]

just forget the thickness and mesh the wall which is in contact with your fluid

[Hershey]

Thank you for your reply -mAx-. I have ended up doing what you said. I seem to be running into the problem with GAMBIT creating default walls in my mesh. For instance, I have split two volumes to allow for the meshing; one small cylinder going into a large cylinder. However, the meshing is fine but when I export the project to a mesh, it creates a wall in between the two volumes which should normally be one continuous fluid.

I am not sure the difference in connecting faces/volumes vs. hard-linking the meshes.

Any ideas?

[-mAx-]

any pictures?

If small cylinder is completly in the bigger cylinder, then you need to split the gigger volume with the smallest. And you delete the smaller cylinder.
Or you can also substract the biggest with smaller.
hard linking is something else.
With picture it will be more clear

[Hershey]

For simplicity, I am attaching a picture with only a single small cylinder inside a larger cylinder. It meshes correctly, however the faces that appear in blue are defaulted as walls by GAMBIT. This is a problem I normally have. I connected the faces that are in the middle of the smaller cylinder and that got rid of the default wall. I am not allowed to connect the faces that are shown in blue though. Just to clarify, the large non-donut face comes from the large upper portion of the cylinder, while the donut face comes from the lower portion of the large cylinder.

Flow is supposed to rise out of the bottom of the small cylinder and out the top of the large cylinder with the freedom to fall down into the bottom of the cylinder.