meshing in GAMBIT, a flow through a pipe having complex inflow geometry
 

i hav developed a geometry in PRO/E, and extracted only the fluid path by cut from option avaliable in pro/e, n exported in gambit as part file.
inlet complex geometry details:
liquid flow through a pipe-
liquid inlet and flowing through an annular space ; then comes in full pipe flow; then passes through orifice plate; then through straight rods (heating source) placed in path of liquid; then again flow out by passing through annular space.
how i can mesh this pipe ?
is it possible to do volume mesh as one volume?

i hav tried by dividing the whole pipe in 15 small volumes in pro/e and then assembled it as the original pipe design, but in fluent the faces of volumes are consider as wall so information from one volume is not transfering to another b/c of wall in b/w 2 volumes.

tell me how i can mesh that complex pipe in gambit

above all steps e.g. dividing into 15 volume etc can be easily done in gambit. post few pics