cellzone defined by two stl files
 

Dear all,

I am trying to create a cellzone using snappyHexMesh.
I would like to define the cellzone volume inside two surfaces (through the corresponding .stl files) instead of single unified surface.

Essentially I am trying to replicate the material point method found in other cutcell meshers, where a cellzone is created by simply supplying a point that lies inside multiple surfaces that form a watertight region/volume.

In the attached figure I have two geometrical features that I would like to use to define the cellzone :
box (yellow )
box_top (blue)

I am therefore trying to create a cellzone inside the feutures box and box_top.

Does anyone know how to do that?

Many thanks in advance.