Different kinds of pressure in FLUENT
 

Dear all,

I'm Mattia and I'm a PhD student at the Delft University of Technology (The Netherlands).

At the moment, I am analyzing a radial compressor by means of CFD: I am using GAMBIT 2.3.16 for mesh generation and FLUENT 6.3.26 for simulations.

At first, I am using a single rotating frame, which means that everything is rotating (both inlet and outlet basically, because that compressor does not have any diffuser).

I got some preliminary results but I am a bit concerned about post-processing relative to the pressure field.

In FLUENT it is possible to plot contours for different types of pressure, bearing in mind that the user's guide define the absolute pressure as sum of operating pressure and gauge pressure. Moreover, the Bernoulli's law says that the total pressure is sum of the static and dynamic (0.5*rho*v^2) pressures. Besides, FLUENT always computes gauge pressures.

Now, how can I be sure about the most important type of pressure for my case? What kind of gauge pressure is the one added to the operating pressure to get the absolute pressure? What is the so-called "relative total pressure"? "Relative" to what?

Thank you. Kind regards, Mattia.