Fresh water flows horizontally from pipe section 1 of cross-sectional area A1 into pipe section 2 of cross-sectional area A2. The figure gives a plot of the pressure difference p2 – p1 versus the inverse area squared A1 -2 that would be expected for a volume flow rate of a certain value if the water flow were laminar under all circumstances. The scale on the vertical axis is set by Δps = 350 kN/m 2 .