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

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,

anyone have an idea about that, and how to resolve this issue? ;)