WK 7

Question 1

define pipes

Answer 1

or ducts

• all cross section taken up with fluid
• known as closed conduit
• characterized usually by a free surface- open to the atmosphere. They include streams, rivers,

Question 2

define open channel

Answer 2

or open conduit

• some of the cross section is taken up with the fluid

Question 3

define hydraulic radius

Answer 3

• hydraulic mean
  depth

The characteristic dimension of pipes and open channels

Question 4

hydraulic radius equation

Answer 4

• A= the geometry of the channel
• P= the sum of the length of the solid boundaries actually in
  contact with the fluid

Question 5

Hydraulic radius for a closed pipe (prove it)

Answer 5

• use A/P equation

Question 6

define uniform flow

Answer 6

If the flow velocity is assumed to have the same speed and
direction at every point within the fluid,

Question 7

define non-uniform flow

Answer 7

If at a given instant, the velocity is not the same at every point,
the flow is non–uniform.

Question 8

label this diagram

Answer 8

Question 9

what conditions apply to:
1) non-steady, non- uniform flow

2) steady, non-uniform flow

Answer 9

1) Every condition of the flow may change with position and time.

e.g. waves in a channel or accelerating/decelerating flow through a tapering pipe

2) Conditions change with position but not with time.

e.g. flow at constant rate through a tapering pipe with constant velocity at the inlet - velocity will change along the length of the pipe towards the exit.

Question 10

define laminar flow

Answer 10

• lower velocities,
• the fluid particles appear to move in straight lines
• although the particle velocity along
  each line may not necessarily the
  same.

Question 11

define turbulent flow

Answer 11

• higher velocities,
• the fluid particles no longer move in straight paths
• but are intertwining and crossing one
  another in a disorderly manner

Question 12

define transition region

Answer 12

region between these two
flow regimes (laminar/ turbulent) known as the transition region.

Question 13

imagine difference in laminar and turbulent flows.

Answer 13

Question 14

What’s Darcy’s equation?

Answer 14

hf= head loss (m)
L= pipe length (m)
U= pipe velocity
d= pipe diameter
Q= flow rate (discharge) m^3/s
g= acceleration due to gravity (9.81 m/s^)
f= friction factor

Question 15

define head

units?

Answer 15

used to describe the energy in incompressible
fluids.

It equals the fluid’s energy per unit weight.

• expressed head in units of height (e.g. metres)
  or in units of pressure such as Pascals (Pa) (the SI unit).

Question 16

define head loss

Answer 16

• measure of the reduction in the total head (sum of elevation head, velocity head and pressure head) of a fluid as it moves through a fluid system.

It is an energy loss.