surface boundaries from solid
 

Hello everyone. I'm new to ansys and I'm trying to model wind flow over terrain in cfx.

I have imported a .stl file in ICEM containing 2 solids,1 for earth terrain and 1 for the atmosphere above. They are not perfect solids, they both have one surface which is the intersection of air and soil (mountainous region).

My problem is that I can't define a boundary from any side of the upper solid (air) for inlet outlet or openning in cfx.While I've created individual surfaces (as individual and not inherited parts) on all sides in icem,cfx cant read them.

I'm missing sometghing here and can't find any info for that.

So the question is ,how can I declare the faces of a solid as boundaries so that cfx can read them?

Any help or suggestion,is most welcomed!