Suggestions on meshing hydrocyclone
 

Dear Friends, At the outset let me wish you all "A VERY HAPPY NEW YEAR" I am working on modelling a hydrocyclone. I would greatly appreciate if some body can clarify my doubts on the following:

1.While making geometry is it required to define a separate air-core? if yes how do we define its boundary conditions at the spigot inlet and vortex finder outlet; if no does the software takes care of the formation of air core because of the centrifugal and drag forces of water (primary phase) 2.Do we need to consider the feed inlet, cylindrical, conical and vortex finders as separate volumes while defining the mesh? if no (a single volume) how do we get different mesh densities at different positionsin the cyclone if yes what are the boundary conditions, how do we define the boundaries of these volumes to maintain the continuity. Thanking you Vaibhav