boundary conditions in un nozzle

[SimoneTecnoil]

Hello, everyone. I have to calculate load losses in a nozzle (varied section changes in practice). I know the incoming water pressure, its temperature and flow. I want to know the output speed (I could also do it manually the sò) and especially the load losses in the nozzle if the input pressure is 10 bar. Now... I am confused between operating conditions and boundary conditions....how do they set? I do not know the outgoing pressure....but I would like to use "pressure outlet" on the exit section because it is more precise...and I put in the "gauge pressure" in the outlet? I don't know him! I'd like to use "mass flow inlet" and there's no problem here. but the 10 bars where you put them? in operating conditions? Help.

 

[Vmax]

regardless of the software, from the physical point of view you need to impose compatible boundary conditions both at the entrance and at the exit. with the sole exception of supersonal flows. Otherwise the problem is not well placed mathematically.
Mathematically it is shown that the input-pressure condition is the most robust setup, other conditions should be evaluated case by case. if you're interested in load losses just then put the pressure in and out.
Hi.
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