1. Water Distribution 1 Water Distribution

2. Water Distribution 2 Introductory Question Water enters your home plumbing at ground level. Where will you get the strongest spray from a shower? Water enters your home plumbing at ground level. Where will you get the strongest spray from a shower? A. In the ground floor shower B. In the basement shower C. In the second floor shower

3. Water Distribution 3 Observations about Water Distribution Water is pressurized in the pipes Water is pressurized in the pipes Higher pressure water sprays harder Higher pressure water sprays harder Higher pressure water sprays higher Higher pressure water sprays higher Water is often stored up high in water towers Water is often stored up high in water towers

4. Water Distribution 4 4 Questions about Water Distr. Why does water move through level pipes? Why does water move through level pipes? How can you produce pressurized water? How can you produce pressurized water? Where does the work you do pumping water go? Where does the work you do pumping water go? As water flows, what happens to its energy? As water flows, what happens to its energy?

5. Water Distribution 5 Question 1 Why does water move through level pipes? Why does water move through level pipes? Can water in a level pipe move without a push? Can water in a level pipe move without a push? How does water in a level pipe respond to a push? How does water in a level pipe respond to a push? How do you push on water in a level pipe? How do you push on water in a level pipe?

6. Water Distribution 6 How Water Moves (no gravity) Water, like all fluids, obeys Newton’s laws Water, like all fluids, obeys Newton’s laws When water experiences zero net force, it coasts When water experiences zero net force, it coasts When water experiences a net force, it accelerates When water experiences a net force, it accelerates Pressure imbalances exert net forces on water Pressure imbalances exert net forces on water Water accelerates toward lower pressure Water accelerates toward lower pressure

7. Water Distribution 7 Question 2 How can you produce pressurized water? How can you produce pressurized water? How can you create pressure? How can you create pressure? How can deliver pressurized water to a pipe? How can deliver pressurized water to a pipe? Why does pumping water require such effort? Why does pumping water require such effort?

8. Water Distribution 8 Pressurizing Water To pressurize water, confine it and squeeze To pressurize water, confine it and squeeze As you push inward on the water, As you push inward on the water, it pushes outward on you (Newton’s third law). it pushes outward on you (Newton’s third law). water’s outward push is produced by its pressure water’s outward push is produced by its pressure the water’s pressure rises as you squeeze it harder the water’s pressure rises as you squeeze it harder

9. Water Distribution 9 Pumping Water (no gravity) To deliver pressurized water to a pipe, To deliver pressurized water to a pipe, squeeze water to increase its pressure squeeze water to increase its pressure until that pressure exceeds the pressure in the pipe. until that pressure exceeds the pressure in the pipe. The water will then accelerate toward the pipe The water will then accelerate toward the pipe and pressurized water will flow into the pipe! and pressurized water will flow into the pipe!

10. Water Distribution 10 Pumping Requires Work You do work as you pump water into the pipe You do work as you pump water into the pipe You squeeze the water inward – the force You squeeze the water inward – the force The water moves inward – the distance The water moves inward – the distance In this case, the work you do is: In this case, the work you do is: work = pressure· volume The pressurized water carries your work with it The pressurized water carries your work with it We’ll call this work “pressure potential energy” We’ll call this work “pressure potential energy”

11. Water Distribution 11 Question 3 Where does the work you do pumping water go? Where does the work you do pumping water go?

12. Water Distribution 12 Pressure Potential Energy Pressure potential energy is unusual because Pressure potential energy is unusual because it’s not really stored in the pressurized water, it’s not really stored in the pressurized water, it’s promised by the water’s pressure source. it’s promised by the water’s pressure source. In steady state flow (SSF), In steady state flow (SSF), which is steady flow in motionless surroundings, which is steady flow in motionless surroundings, promised energy is as good as stored energy promised energy is as good as stored energy pressure potential energy (PPE) is meaningful pressure potential energy (PPE) is meaningful

13. Water Distribution 13 Question 4 As water flows, what happens to its energy? As water flows, what happens to its energy?

14. Water Distribution 14 Energy and Bernoulli (no gravity) In SSF, water flows along streamlines In SSF, water flows along streamlines Water flowing along a single streamline in SSF Water flowing along a single streamline in SSF has both PPE and kinetic energy (KE), has both PPE and kinetic energy (KE), must have a constant total energy per volume, must have a constant total energy per volume, and obeys Bernoulli’s equation (no gravity): and obeys Bernoulli’s equation (no gravity): PPE/Vol + KE/Vol = Constant/Vol

15. Water Distribution 15 How Water Moves (with gravity) Weight contributes to the net force on water Weight contributes to the net force on water Without a pressure imbalance, water falls Without a pressure imbalance, water falls Water in equilibrium has a pressure gradient Water in equilibrium has a pressure gradient Water’s pressure decreases with altitude Water’s pressure decreases with altitude Water’s pressure increases with depth Water’s pressure increases with depth Water has gravitational potential energy (GPE) Water has gravitational potential energy (GPE)

16. Water Distribution 16 Energy and Bernoulli (with gravity) Water flowing along a single streamline in SSF Water flowing along a single streamline in SSF has PPE, KE, and GPE, has PPE, KE, and GPE, must have a constant total energy per volume, must have a constant total energy per volume, and obeys Bernoulli’s equation (with gravity): and obeys Bernoulli’s equation (with gravity): PPE/Vol + KE/Vol + GPE/Vol = Constant/Vol

17. Water Distribution 17 Energy Transformations (part 1) As water flows upward in a uniform pipe, As water flows upward in a uniform pipe, its speed can’t change, so its speed can’t change, so its gravitational potential energy increases its gravitational potential energy increases and its pressure potential energy decreases. and its pressure potential energy decreases. As water flows downward in a uniform pipe, As water flows downward in a uniform pipe, its speed can’t change, so its speed can’t change, so its gravitational potential energy decreases its gravitational potential energy decreases and its pressure potential energy increases. and its pressure potential energy increases.

18. Water Distribution 18 Energy Transformations (part 2) As water rises upward from a fountain nozzle, As water rises upward from a fountain nozzle, its pressure stays constant (atmospheric), so its pressure stays constant (atmospheric), so its gravitational potential energy increases its gravitational potential energy increases and its kinetic energy decreases. and its kinetic energy decreases. As water falls downward from a spout, As water falls downward from a spout, its pressure stays constant (atmospheric), so its pressure stays constant (atmospheric), so its gravitational potential energy decreases its gravitational potential energy decreases and its kinetic energy increases. and its kinetic energy increases.

19. Water Distribution 19 Energy Transformations (part 3) As water sprays horizontally from a nozzle, As water sprays horizontally from a nozzle, its height is constant, so its height is constant, so its kinetic energy increases its kinetic energy increases and its pressure potential energy decreases. and its pressure potential energy decreases. As a horizontal stream of water hits a wall, As a horizontal stream of water hits a wall, its height is constant, so its height is constant, so its kinetic energy decreases its kinetic energy decreases and its pressure potential energy increases. and its pressure potential energy increases.

20. Water Distribution 20 Introductory Question (revisited) Water enters your home plumbing at ground level. Where will you get the strongest spray from a shower? Water enters your home plumbing at ground level. Where will you get the strongest spray from a shower? A. In the ground floor shower B. In the basement shower C. In the second floor shower

21. Water Distribution 21 Summary about Water Distribution Water’s energy remains constant during SSF Water’s energy remains constant during SSF Water’s energy changes form as it Water’s energy changes form as it flows upward or downward inside pipes, flows upward or downward inside pipes, rises or falls in open sprays, rises or falls in open sprays, and shoots out of nozzles or collides with objects. and shoots out of nozzles or collides with objects. Water distribution can driven by Water distribution can driven by pressurized water (PPE) pressurized water (PPE) elevated water (GPE) elevated water (GPE) fast-moving water (KE) fast-moving water (KE)