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Pressure of Reservoir

  1. Mar 15, 2009 #1
    1. The problem statement, all variables and given/known data
    What pressure Pr, is required to achieve a flow rate of 10 m/s into the underwater reservoir if the tank is 100 m below the surface. Liquid ammonia is to be transferred with a density of 682 kg/m^3 and the pipe diameter is 5 cm. The reservoir underwater is at local hydrostatic pressure. A picture is included.

    2. Relevant equations

    Bernoulli's Eqn: P1 + (1/2)[tex]\rho[/tex]U2 +[tex]\rho[/tex]gz

    3. The attempt at a solution
    At first I thought that it was as simple as plugging in the values given into the formula and solving for P1, but then I realized that they gave us the diameter of the pipe too so I'm guessing it has some significance. I can't seem to figure it out though, any help would be great.

    http://i429.photobucket.com/albums/qq12/ACE_99_photo/Untitled-2.jpg" [Broken]
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 15, 2009 #2


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    Hi Ace. Bernoulli's equation is just one of the necessary equations to calculate this. The other is the irreversible pressure drop of fluid that flows through a pipe which is best done using the Darcy Weisbach equation. You can plug the DW equation into the B equation simply by recognizing that there is a permenant pressure drop under flow equal to the pressure predicted by the DW equation.

    Take a look at the DW equation and try to understand how the flow of fluid corresponds to some pressure drop in a pipe.
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