Hi,
I am trying to create a volume tetrahedral mesh between two surfaces, I need to close the top and bottom caps of my structure (below is a section of the model).

I am facing two issues:
1. I need to keep the same topology (map) of these surfaces, in other words the positions of the nodes.
2. I need a bigger size elements in the middle of the mesh to reduce the computation time.
the aim is to get a mesh that look like this

I highly appreciate your help,
Many thanks,
Farah