Axial flow turbine approperiate B.C

dia aisa

dear my problem is how to define the boundary condition well,now i set the mass flow rate for inlet and p-static at outlet(p-static=1atm),please what approperiate BC for axial flow water turbine kaplan if the net head is 40m and mass flow in about 116 meter cube/s.also how to present av static pressur is a presssure at required location denote to static pressure.or there is another method to calculate av static pressure