I have run a FloXpress study, by entering the volumetric flow rate into the inlet opening, and it has reported the flow velocities throughout the model.  My understanding is that FloXpress reports results only as velocities.  I would like to know the pressure difference between the inlet and the outlet.  Since flow resistance is approximately proportional to the square of the velocity, I would also expect the pressure difference to vary with the velocity squared.

I could repeat the study, except instead of entering volumetric flow rate, I would enter an inlet pressure, and then compare the resulting velocities with the ones generated by the simulation in which the volumetric flow rate at the inlet was entered.  I could repeat the study by entering various inlet pressures until the velocities are approximately equivalent to the velocities that were reported when the volumetric flow rate was entered.  Once I select the inlet pressure that results in approximately the same velocities reported by the volumetric flow rate run, is it valid to infer that the pressure delta gives rise to the flow rate of the first simulation?