about degassing BC
 

Hi all
I'm doing simulation by using VOF and DM with FLUENT
There are two phases like air, water in square .
then both air and water are compressed from bottom surface like piston moving.
all BCs are wall
but i want to make onlly air out at the top of the wall.
So Plz give me the UDF for degassing example.
I don't have any degassing UDF examples.
Plz email to me
rjhlbs@hotmail.com
plz

I have the same question as you.I want to define a free surface which gas can vent out freely but liquid can not get out.But i don't know how to define such a boundary condition in a udf file.Can anyone help me and give me a example udf about it.