Uniting Two Volumes Into One Flow Domain

I wish to model a vertical two-phase separator. I have prepared the geometry of the vessel: A vertical cylinder with on horizontal inlet no the side, a vapor out on top and liquid outlet on bottom.

There is to be liquid level in the bottom of the vessel. The remainder of the vessel is vapor space.

I created two volumes from the initial single volume using the Decompose Booleans operation. One volume for vapor and one for liquid.

How do I now unite these volumes into a single flow domain so I can create initial liquid level conditions and mesh the geometry? I'm stuck at this point...

My ultimate goal is to measure the shear on the face of liquid surface caused by the vapor entering the vessel.


Connect Faces and apply substance to volume group

For a multi-volume flow-domain:

  1. On the Geometry Tool Palette use the Faces->Connect tool to connect the co-located faces between the 2 volumes as in the tutorial "Water Tank".
  2. Create a group of the 2 volumes and apply the Substance (Air+Water) to the group as in the tutorial "Transient Water and Air Flow in a Tank".

Make sure you don't apply a boundary condition to the connected face(s) to ensure it remains an internal fluid interface.

You will be able to visualize the effect of the vapor flow (using iso-surfaces of velocity magnitude) across the liquid surface, but actual shear force is only available on walls.