Shadow Wall
 

What is the story behind this shadow wall thing? (when you have solid / fluid interface) What does it do?

Re: Shadow Wall
 

a 2d surface that is defined as a wall with the domain on both sides will be split into 2 walls, one for each side, so that you can define a different bc for each.

If its not supposed to be a wall, then pick one of them and redefine it as an interior.