Harmonic Analysis downstream of orifice plate?

Taking a 500+ psi drop across and orifice and trying to perform a harmonic - fatigue analysis of piping downstream.

Fluid is nitrogen gas and the orifice is assumed choked. Applying the "Harmonic Frequencies" of between 0.2 V/D and 0.3 V/D produces obvious high frequencies (1500 - 2500 Hz).

Applying the phase formula for the high frequency, relatively short pipe length results in a phase number that doesn't make sense (a number greater than 360).

I guess my basic question is, "Is this type of application something that Caesar II is capable of performing?".

For a harmonic analysis is c2, you have to define the harmonic forcing frequency and either the applied force or the applied displacement. c2 will then determine the deflection and stress in the piping system as a result of this harmonic load.

c2 will not assist in determining the applied load.