Orifice
 

how can i do this simulation?

you have to know the mass flow through the orifice plate. So can use either mass flow inlet/velocity inlet - pressure outlet or pressure inlet - mass flow outlet combinations. If you are using a velocity inlet boundary conditions and if it is a fully developed turbulent flow make sure you use a udf or user defined profile to define the fully developed turbulent velocity profile at inlet.

here is a useful material, but it is for laminar,

http://research.me.udel.edu/~lwang/teaching/MEEG102/

Yes, you can model this. But what do you want to get out of the model? Pretty pictures? Pressure drop? Flow cross section?