plz help its urgent
 

hi

thanx for ur guidance

ok if the backflow volume fraction for the phase which is not being asked is taken as 1-(the volume fraction specified for other phase), then can u plz tell what boundary condition shud i take if i want the following situation to model:

my system consists of a rotating cylinder(i.e. rotor of the centrifugal contactor) in which i m employiong the use of VOF model to simulate fluid flow in it. the cylinder has an inlet at the bottom thru which water enters and it goes out thru the top annular ring. this annular ring at the top is defined as pressure outlet b.c. , also there is a small opening at the centre of the top which lets the water rotating in cylinder exposed to atmosphere. so there are 2 fluids air and water. now at the top where i hav specified pressure outlet b.c. i need only water to leave out and no backflow of it and also no air shud come in or going out thru that opening then how shud i employ that .

plz guide thanks

garima