Gambit - Problem having shadow wall on volume
 

I've constructed a 3d file in gambit to model heat and mass transfer from a leaf. I have a rectangular volume made and i made a volume inside the rectangular volume to be the leaf.

After meshing the inside the leaf volume with hex/wedge cooper and the rectangular volume using hex map, specifying the zones and exporting it to fluent, under boundary conditions, there is just leaf, there is no leaf_surface which I need for some user defined functions.

What do I need to change in gambit so that I can get the leaf to have the leaf shadow as well?

you need to split or substract.
Post a picture or a sketch

http://imageshack.us/photo/my-images/138/leaf3d2.png/

There's the picture of the gambit file before I meshed bot the inside of the leaf volume and then the overall volume. I tried subtracting the leaf volume from the rectangular volume, but then it won't mesh using the same hex method.

ok then if you substract the leaf from the rectangular volume, and you cannot mesh the volume with hex anymore, that means you are on the right way.
Thus you cannot mesh non-basic volume with hex automatically.
You need to split your volume, into smaller volumes, which will be hex- meshable