numerical simulation of a hydrocyclone
 

I am now carrying out a numerical simulation of hydrocyclone, using FORTRAN program, not commercial software such as FLUENT, CFX. I find it very difficult, for example, 'WALL FUNCTIONS", as you know, a simply hydrocyclone consists of two parts: the cylinder part, and the conical part.

"WALL FUNCTIONS" are derived from a one-dimensional steady Couette Flow analysis of the wall-layer as a function of the local Reynolds number y+. To vertical or horizontal wall it is easy to deal with (just with some judgement sentences and some evaluating sentences). But in terms of a slope, how to carry out the "WALL FUNCTIONS" in the conical part?

I am eager to get your help, thanks a lot!