Figure 2
From: Magnetic resonance velocity imaging derived pressure differential using control volume analysis
Schematic of the flow phantom experiments. During experiments the pressure taps were in a horizontal plane (ie. gravity is perpendicular to the figure plane). The cylindrical passage is enlarged to show the control volume of interest with axial length L between pressure taps. Long bold arrow points in axial direction and short bold arrow depicts the unit outward surface normal vector, 
. PC-MR velocity measurements were obtained independent of pressure data under the same imposed flow waveform. DAQ - Data acquisition electronics.