I'm simulating a Pelton turbine nozzle in Flow Simulation. I know the rated head of the turbine (121.6 m), and the required discharge (Q=0.19 m3/s), and that the discharge is to the atmosphere. My Boundary conditions are the inlet flow (Q=0.19 m3/s), and environmental pressure in the outlet. I'm doing a parameter study with goal optimization to find how open should be the valve for my conditions (that is, until the required pressure is found). My question is, which pressure should be the goal as static pressure at the inlet?

Rated head (121.6 m) which is the gauge pressure?
Absolute pressure (121.6 rated head+10.32 atmospheric) ?

Or should I set the goal as Total pressure inlet for one of the above options?

I hope my question is clear. Please let me know if you need any clarification.

Thank you very much!