Test 3

Question 1

Why do we need Momentum Eq?

Answer 1

1. Energy Loss – Hydraulic Jumps
2. Steady non-uniform flow
3. Forces on hydraulic structures
4. Design

Question 2

What are the momentum assumptions?

Answer 2

Theta = zero
Frictional force is neglected

Question 3

Energy V.S. momentum

Answer 3

Energy
* Scalar
* Internal Losses
[Friction]
* Channel Transitions
Momentum
* Vector
* External Resistance
[Friction Obstruction]
* Forces on Obstructions
* Hydraulic Jump!!!

Question 4

What is the main purpose of a hydraulic jump?

Answer 4

To Dissipate energy

Question 5

What are other applications of a hydraulic jump?

Answer 5

Prevent scouring
Raise water level
Mixing
Aerate water

Question 6

How are hydraulic jumps classified

Answer 6

By upstream Froude number

Question 7

what is constant in uniform flow

Answer 7

y, v, A and Q are constant at
every section of channel
reach

Question 8

What do we care about unifiorm flow?

Answer 8

Flow is always trying to reach
uniform flow
Flow assumes uniform flow
under normal conditions

Question 9

what is bormal flow a function of?

Answer 9

yn = f(Q, geometry, So, Resistance)

Question 10

What is critical flow a function of?

Answer 10

yc = f(Q, geometry)

Question 11

How in manning’s n determined?

Answer 11

• No exact method…Resistance to
  flow difficult to find
  1. Understand factors and guess
  2. Match known values to photos
  3. Tables!
  “Max is most Conservative”

Question 12

What factors effect manning’s n?

Answer 12

• Surface roughness
• Vegetation
• Channel Irregularity
• Channel Alignment
• Silting and Scour – Bed Movement
• Obstructions
• Size and Shape
• Stage + Discharge
• Seasonal Change
• Suspended Sediment