You can write the boundary zones (surface mesh) to a file. This file can be read and used by the meshing mode of Fluent to produce a volume mesh. You may find this feature useful if you are unsatisfied with a mesh obtained from another mesh generation program.

A boundary mesh can be written using the Select File dialog box, opened by selecting the File/Write/Boundary Mesh... ribbon tab item.

 File → Write → Boundary Mesh...