In modeling incompressible air flow in 3D through a section of pipe, how would you correctly determine the pressure drop between the inlet and outlet???

Would you use:

Difference in Static or Total Pressure Values?

Secondly, how would you obtain these values at the inlet and outlet (i.e. surface integral using area-weighted-average, mass-weighted-average, facet-average, etc.)?

Lastly, I am given the mass flow rate at the inlet boundary to this pipe section and that it is incompressible air flow....the point again is to determine the pressure drop across this section of pipe.....FLUENT manual suggests using Velocity Inlet and Pressure Outlet, but could I get away with using: (Mass-Flow-Inlet with Outflow-Outlet) or (Mass-Flow-Inlet with Pressure-Outlet static pressure set to zero)??? Do I have to use periodic conditions at inlet and outlet to get fully developed profiles first???

Any help, comments, or suggestions in regards to any of the above questions is GREATLY appreciated!

Thanks for your time! Joe

I think "pressure drop" you meant is head loss which usually implies decrease in total pressure. Text book of Anderson about Fluid have a good explanation about this.

thanks