[Gigaincfd]

Hi,
i arrive now in this forum.You are very wonderfull,i found many useful things here.
I have a question:
I am studying the discharge of a vessel with internal upper pressure.
I would like to know how long a vessel is discharged with a positive pressure.
A vessel has 3 orifices.
I try to make a unsteady symulation but the discharge time is very very high.
cfd approach is wrong? is it possible to set up a simulation?
thx a lot