[Ema40]

Dear all.

I am simulating an open channel flow (multiphase VOF), in particular a subcritical flow, so I need a specific outlet (or downstream) BC, in particular the water depth. If I do a transient (unsteady) simulation, is it right to impose this downstream BC?
Because, let's you imagine the phisics of the transient time; the channel begins to be filled by water from the inlet; if this water has not still reaches the outlet, how the flow can "understand" the downstream water depth BC that I imposed? Thus, is it right to impose this BC for an unsteady simulation?

Thank you