[Luk_Fiz]

Hi all,
I have a simple question that is maybe more related to physics not CFD itself. The simulated arrangement is very simple: Outflow of the water to air through the pipe (it is a kind of valve), the outlet of the pipe is approximately 5 mm. The velocity of the water is approximately 100m/s. Physical testing shows, that the outflow with this velocity produces spray or mist rather than water flow.
My question is: what is a most appropiate outlet boundary condition (simlating only a pipe, not a pipe outlet and some air volume)?. Setting "Opening" with relative pressure 0 overpredicts mass flow. I guess that there is some kind of aerodynamic drag of such a spray but looking through literature I cannot find anything seriously usefull. Can anyone tell anything about the "drag" of the waterflow into a gas?

Thanks a lot,
Luk