Two phase flow VOF ( fluid didn't fill the whole pipe)
 

Hello I have question I'm modeling 2 phase flow
Boundary condition : Mass flow rate inlet one for Air only and the other for water
Steady state solution
ِAir as primary phase
Water secondary phase

the question , why didn't the water fill the pipe till the end ?
(attacked photo )

http://imgur.com/1OLWGVl

I tried before to simulate transient flow and increased the simulation time and same thing happened
Any help ?

Try to set slip wall condition at the walls. If by doing so it happens would logics says it might be that you are facing the discontinuity of the NS equations due to a moving contact line with a no-slip BC.