Lecture 2

Question 1

Why technique generates hydrogen bubbles in the water

Answer 1

Electrolysis

Question 2

What is the main use of the hydrogen bubbles

Answer 2

Visualisation technique

Question 3

Is hydrogen bubbles qualitative or quantitative

Answer 3

Qualitative

Question 4

What is the term given to a dye added to a flow experiment

Answer 4

Flow tracer

Question 5

How do you get a sequence of straight lines in the flume

Answer 5

Pulse the electrolysis

Question 6

What shape bubble system is used to show flow

Answer 6

Square

Question 7

What shape will the squares look like if the water flow is even

Answer 7

Even shape, pattern in even

Question 8

What is it called when water moves up in the column

Answer 8

Ejection/ Bursting

Question 9

What is it called when water moves Down in the column

Answer 9

Inrush/sweep

Question 10

What is the most important thing in sediment entrainment and transport

Answer 10

Turbulence

Question 11

What is ADVP

Answer 11

Acoustic Doppler velocity profiling

Question 12

How can the Doppler effect monitor flow rate

Answer 12

Uses shift from scattered sound to measure velocity

Question 13

What point is 0 in relation to a Doppler probe

Answer 13

The futhest point away

Question 14

What is good about the Doppler technique

Answer 14

Gives a lot of detail about the flow patterns, much more than just the bubbles

Question 15

What directions can water move in

Answer 15

Water can go downhill, back on itself, move left and right and up and down

Question 16

Which technique can measure the entire flow field

Answer 16

Particle imagine velocimetry

Question 17

What are put into the tank so that the pictures can calculate flow

Answer 17

Little spheres that are used to track flow

Question 18

How is the image captured using the PIV

Answer 18

Laser flashes while camera takes photo

Question 19

What is the equation for Working out movement

Answer 19

U=x/t

Question 20

What is an ecm

Answer 20

Electromagnetic current meter

Question 21

What forces control the behaviour of fluids

Answer 21

Inertial gravitational and viscous

Question 22

What is the Reynolds number

Answer 22

Discriminates between laminar and turbulent rates

Question 23

What is the equation for Reynolds number

Answer 23

Re=pul/u

Question 24

What is the flow of the Reynolds number is less than 500

Answer 24

Laminar

Question 25

What is a turbulence Re value

Answer 25

Above 2000

Question 26

What is the equation for froude number

Answer 26

Fr=u/^gl

Question 27

What is the ratio concerned with in the froude number

Answer 27

Ratio between Inertia and gravity

Question 28

What does u represent in terms of rivers and the water system

Answer 28

Water velocity

Question 29

What does l represent in river systems

Answer 29

Depth

Question 30

What is the fluid state if Fr>1

Answer 30

Super critical

Question 31

What happens if the froude number is <1

Answer 31

Subcritical

Question 32

Which directions can water move in if the flow is subcritical

Answer 32

All directions

Question 33

Supercritical flow is most likely where

Answer 33

Fast flow in shallow depths

Question 34

What can froude numbers of flow impact on

Answer 34

Bed form creation

Question 35

What froude numbers are most rivers

Answer 35

Less than 1

Question 36

What is shear stress

Answer 36

Force of the flow on the river bed

Question 37

What is the equation for average shear stress

Answer 37

T=pgRS

Question 38

What is The hydraulic radius

Answer 38

The cross sectional area divided by the wetted perimeter

Question 39

What does S stand for in the shear stress equation

Answer 39

Slope

Question 40

How do we normally get hydraulic radius

Answer 40

Approximate the mean depth

Question 41

What are the advantages of averaged methods

Answer 41

Serves an index of the total resistance by all frictional influences on the flow and easy to measure

Question 42

What are the disadvantages to Average shear stress

Answer 42

Does not provide information on spatial variation at reach sub scale not a good index of the ability for the sediment to move to the next section

Question 43

what is the no slip condition

Answer 43

particles in contact with a surface will move the same speed (or no speed) of that surface

Question 44

What is non uniform flow

Answer 44

flows were cross sectional area and velocity changes

Question 45

what is dynamic pressure

Answer 45

pressure exerted by a moving fluid

Question 46

what is a stream (dingman)

Answer 46

any body of water flowing with measurable velocity in a channel

Question 47

what is a stream reach

Answer 47

a stream segment with fairly uniform size and shape, slope, channel materials and flow characteristics