Strange results with different boundary conditions
 

Hi there!
I really need to understand why I get strange results in my simulation. It is about the power generated by a cross flow turbine (Banki). I am using mixture model of two phases : water and air. The water enters a nozzle that discharges it into a runner. The water passes through it and then exits from my domain.
In the experiment the water has a head of 6.5 m and a mass flow rate of 0.85m3/s.
First I imposed at the nozzle's inlet a mass flow boundary condition and at the exit an 0 pressure outlet boundary condition. The converged steady solution shows me a total pressure at inlet of approx 1atm but I expected 0.63 atm ( rho*g*h the hydrostatic pressure).
If I impose the total pressure at the inlet I don't get the mass flow expected.
What am I doing wrong?
Thank you all!

Some pictures
 

https://www.dropbox.com/s/feyglkup0e...re%20inlet.jpg

<a href="https://www.dropbox.com/s/8r72cfl8p9hwh2k/steady_pressure%20inlet1.jpg" target="_blank"><img src="https://www.dropbox.com/s/8r72cfl8p9hwh2k/steady_pressure%20inlet1.jpg" border="0" alt="dropbox" /></a>