Netgen can be alerted to close surfaces which will automatically trigger prismatic element generation. Here are two examples:
The first example shows how thin annular rings can be meshed by curved prisms.
The second example meshes a flat thin layer using prisms, which can be seen after zooming into the thin layer in the middle of the meshed box.
Sometimes we have a situation where two pairs of close surfaces intersect, such as in this figure:
In such cases, Netgen will attempt hexahedral element generation at the intersection, match it with prisms surrounding it, and transition to tetrahedral mesh using pyramidal elements. Here is an example:
The generated mesh, when zoomed in near the middle thin layer shows a ring of hexahderal elements:
