Exam 1

Question 1

What do water resource engineers do?

Answer 1

1. Water supply
2. Flood protection
3. Power generation
4. Floodplain management
5. Dams
6. Storm sewer design
7. Collection systems

Question 2

3 fundamental principles

Answer 2

Conservation of mass (continuity equation)

Conservation of energy (first law of thermodynamics)

Conservation of momentum (newtons 2nd law)

Question 3

Viscosity (u)

Answer 3

proportion of viscous shear resistance and the rate of change in velocity

Question 4

kinematic viscosity (v)

Answer 4

the ratio of viscosity divided by density

Question 5

Change in pressure equation

Answer 5

Delta P = gamma ( delta z)

Question 6

What are perpendicular forces called

Answer 6

Normal forces

Question 7

Absolute pressure

Answer 7

Measured relative to zero pressure, includes atm pressure

Question 8

Is flow a scaler or vector

Answer 8

scaler

Question 9

Reynolds # for turbulent and laminar

Answer 9

RE<2000 laminar
Re > 4000 turbulent
2000 < Re < 4000 transition

Question 10

Uniform Flow

Answer 10

streamline parallel, velocity does not change over distance

Question 11

Nonuniform flow

Answer 11

converging or diverging streamlines

Question 12

Does uniform flow mean uniform velocity

Answer 12

NO, there is a velocity gradiant

Question 13

Q = intergral (V*dA),
What is dA for a cirlce
A rectangle?

Answer 13

circle - 2pir*dr
rectangle - Base * dy

Question 14

Steady Flow

Answer 14

Velocity constant over time

Question 15

Unsteady flow

Answer 15

Velocity changes over

Question 16

What is the continuity equation

Answer 16

(dS/dt) = Qin - Qout
change in storage over time

Question 17

What is the energy equation

Answer 17

P/gamma+v^2/2*g+z + Hp = “+ “ + “ +HL + Ht

Question 18

What to change in energy equation in a channel

Answer 18

Change P/gamma to y = depth
This is because pressure is equation to gamma * height so the gamma cancels

Question 19

HGL

Answer 19

hydraulic grade line

Question 20

EGL

Answer 20

Energy grade line

Question 21

Slope of EGL line sf =

Answer 21

HL/ length

Question 22

Why do we care about headloss for design

Answer 22

Money - more energy needed

Question 23

Hf equation

Answer 23

f (L/D) (V^2/2*g)

Question 24

What is f for lamiar flow

Answer 24

64/Re

Question 25

Type 1 problems

Answer 25

Solve for HL Know Q and D 1. find reynolds 2. determine laminar or turbulent 3. use ks/D and find f on moody diagram 4. solve using Darcy Weisbach equation

Question 26

Type 2 problems

Answer 26

Solve for Q or V HL and D known 1. write out friction equation 2. estimate a friction factor using the moody diagram (assume full turbulence) 3. determine velocity from the friction equation 4. Find reynolds number with calculated V 5. Check on moody diagram and find f 6. check and see if f matches earlier estimate if not repeat

Question 27

Type 3 problems

Answer 27

Solve for Diameter Know V and Hl 1. Write our Darcy friction equation 2. Estimate friction factor (start with 0.02) 3. solve for D using assumed f 4. with that D find reynolds number 5. check moody diagram and find f 6. repeat until f matches

Question 28

In a jet of water the point of maximum velocity and min diameter is known as

Answer 28

Vena Contracta

Question 29

HLm equation

Answer 29

= k(v^2/2*g) Always use the faster velocity if the diameters are different