Absolute/relative pressure offset - CFD

Hello everyone,

I am writing on the forum because I have some doubts about the absolute/relative pressure setting in the CFD analysis of a duct. Specifically, I need to evaluate the pressure drop in a duct where I impose the inflow, using the appropriate condition with velocity profile, and the outflow has zero pressure.

If you set the pressure offset to either 101325 Pa or 0 Pa, you will always get the same result. I would like to note that the fluid conditions are at atmospheric pressure, and the outlet condition is at 0 Pa. Therefore, I ask if I need to set other conditions to obtain the pressure drop in this circuit, or if the way I am setting it up is correct in my case (i.e., with a 101325 Pa, or 0 pressure offset), or if other settings are necessary because is not clear if the zero pressure at the outlet take into account the absolute pressure or not.

I'm doing all of this simulation into SimLab 2022.3 and I'm using the solver setting with absolute pressure offset. The fluid is water.

Tanks to all