Can anybody tell me how to create a hemispherical boundary? I need to simulate air flow inside a hemisphere but can't make the shape to do so. Any advice would be appreciated.

Hmmm, If I recall the Phoenics training class I took a decade ago, I think you would make a 3-dimensional domain filled with, say, wood, then you would put a hemisphere object into the domain, and make the hemisphere made out of "air." You will have to use parsol. It might also be a good idea to use cylindrical coordinates so at least one dimension is parallel to your grid axes.