A necked-down section in a pipe flow, called a venturi, develops a low throat pressure that can aspirate fluid upward from a reservoir, as in the figure below.
Consider a venturi used to pull gasoline (SG=0.72) up from a fuel tank. The fuel in the tank is exposed to atmospheric pressure, and the air entering the venturi is traveling at 3 m/s through a 5 cm diameter tube. The fuel needs to be pulled up a 10 cm section of hose (measured from the fuel surface). What throat diameter would allow for the fuel to barely be pulled into the airstream? Does this represent a maximum viable diameter or minimum viable diameter?
