Hi,
I have some problem with my model. It is about water pouring from surface of a soil column. The bottom of the soil column is bounded (also the vertical wall). Thus, the air inside soil must be replaced by water and then escapes to the soil surface as bubbles occurring. I am thinking to make a two-phase flow which can explain the behaviours of both water and air during the process. But it seems to be really difficult to apply both Hydraulic head (for wetting fluid) and Atmosphere/gauss (for nonwetting fluid) to surface boundary condition together. Also, I tried to make the step function but I failed to use it so many times.
Can anyone help me for that?
Thanks in advance!