I'm currently thinking about h
 

I'm currently thinking about how boundary conditions are implemented on free surfaces.

I'm using the interFoam solver.
On a free surface I presume the following (boundary) conditions have to be specified:

Tension normal to the surface = surface tension
Tension tangential to the surface = zero.

(Is that right so far?)

At which step are these conditions implemented in interFoam and how can they be set up?

Well, the surface tension is rather easy by setting sigma ....

Thanks for any help!

Greetings.