VOF modelling, water drainage from an elevated tank
 

Hi,
I am trying to simulate water draining from at a tank at 10 meter elevation through a pipe by the aid of gravity. As seen in the figure 1
[IMG]file:///C:/Users/USER/Desktop/ASHRAF/preliminary%20Geometry_1.png[/IMG]
I am using ANSYS FLUENT to do that. I am using VOF for modelling.
I am having difficulties in defining the inlet and outlet boundary condition.
Right now, I am using pressure-inlet and pressure-outlet for inlet and outlet boundary conditions,
but after running the code,the results is as shown in figure 2,
[IMG]file:///C:/Users/USER/Desktop/ASHRAF/preliminary%20Geometry_2.PNG[/IMG]
file:///C:/Users/USER/Desktop/ASHRAF/preliminary%20Geometry_3.PNG
anyone have an idea about that, and how to resolve this issue? ;)