Problems about multi swirl tubes simulation using Fluent

Here I am doing the research about multi swirl tubes simulation using Fluent. Now some problems puzzled me for some time. Can some one give me better ideas about that? So much thanks for your kind help.

Gambit is uesed for the model, and the deck consists of 10-12 tubes.

1) I wanna calculate the flow rate distribution of inlet room, that is to calculate the every single inlet velocity. How do I set the Boundary Condition for single inlet for calculating ?

2) Beacuse the tube model is the same dimension, so the pressure drop of every tube is the same. If I want to set the same shape tube with different pressure drop, how can I set the initial condition ? Maybe I can change the roughness of tube to realize this purpose. How can I set the roughness in Fluent ?

Best thanks for your suggestive advice.

thanks for all kinds reply!

Can you give more descrpition about the geometry?

Sure. That is called paralell "multi-cyclones". There are 12 the swirl tubes with guide vanes. But how can define the BC of tubes. Two purpose: 1) The flow distribution of every single tube. 2) How to set the pressure drop of every tube, like the industrial condition within 5% pressure drop error or so.

please some body help me!