[kjetil]

Hi,
as a part in a more extensive case, I'm setting up a rather simple case using a siphon and solver compressibleInterFoam. My intentions are to make this system run "by itself", meaning that the flow inside - say a liquid like water - starts from velocity 0, and by itself moves towards the outlet.

So far - by setting the initial conditions improperly - I have managed to get the flow go the opposite way, from bottom to top (see attached file). So my question is:

-what may the correct U and p BC for inlet and outlet be in this case? which should be defined as absolute, or be zeroGradient? As I will introduce a second phase in the flow later, I was hoping to make the boundary conditions as "general" as possible...

Thanks.