hello

i am using VOF model for simulation in a 3d vertical pipe with air water flowing through it. I have defined the inlet velocity condition of the water from the bottom inlet while the air is from the side inlet and is only defined by void fraction = 1 at that inlet.The exit is the pressure outlet. The problem i am experiencing is that even after flow time of 8 seconds have gone the void fraction of air is still 0.0 value at the outlet indicating that air is not entering from the side inlet (although i did place the VF=1 at that boundary condition.

can someone guide me more on this issue. thanks

Can be more clear... What do u mean by VF=1? volume fraction of air is 1 or water?

Hi Manoj

thanks for the reply ............ i have given value of volume fraction of air as 1 at the side inlet that is just for air entrance (not mixture - water+ air). I am monitoring the volume fraction of air near the outlet which does not indicate the air presecne in the pipe even after 8 seconds.

cheers

Aly

just a thought.. maybe the water flow is high enough to cause the air inlet to reverse flow.. in simpler words.. instead of air coming in through the side inlet, water is flowing out through it.. I would recheck the boundary condition for both inlets.