meshing an outer volume to meet inner meshed volume
 

Here is a screenshot for a basic case of what I want to do.
http://imgur.com/ZpAvK

Essentially, I'd like to mesh the inner volume at a fine mesh to capture certain physics. Then, as you can see, I've applied boundary layers to the faces of the outer volume, but because that volume contains a void, I can't map mesh it.

I'd like to mesh the outer volume in such a way that it meets the finer resolution of the inner volume. I also need to keep the mesh orthogonal.

Any ideas or help would be appreciated.

split outer volume with inner volume