# Pressure of Reservoir

1. Mar 15, 2009

### ACE_99

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)$$\rho$$U2 +$$\rho$$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. Mar 15, 2009

### Q_Goest

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.