Lectures 9-10

Question 1

In a rough pipe, the shape of the velocity profile created by the turbulent fluid will be

Answer 1

more rounded and pointy

Question 2

In a smooth pipe, the shape of the velocity profile created by the turbulent fluid will be

Answer 2

more flatter and less pointy

Question 3

Laminar flow compared to turbulent flow has a velocity profile that is

Answer 3

more pointy down the neutral axis of the pipe

Question 4

Laminar flow is not affected by the —– — — —— when creating a velocity profile for it

Answer 4

roughness of the pipe

Question 5

Between 2000-4000 Reynold’s number, the flow is usually

Answer 5

transition flow

Question 6

Under 2000 Reynold’s number, the flow is usually

Answer 6

laminar

Question 7

Above 4000 Reynold’s number, the flow is usually

Answer 7

turbulent

Question 8

Re =

Answer 8

Reynold’s number =

(ρ v D) / μ

( density of fluid X avg velocity X diameter ) / dynamic viscosity

Question 9

The entrance flow is

Answer 9

the distance it takes for a fluid to enter a pipe and fully develop it’s velocity profile

Question 10

Does the reynold’s number have a unit?

Answer 10

No

Question 11

If static pressure decreases, —– —— increases

Answer 11

dynamic pressure

Question 12

When the fluid is in the entrance flow, the drop in ——- ——– drives the fluid forward by converting the pressure to ——– ——-

Answer 12

static pressure, dynamic pressure

Question 13

Friction force depends on three main characteristics:

Answer 13

• solid characteristics
• fluid characteristics
• relative velocity

Question 14

Solid chracteristics include 2:

Answer 14

• geometry (size D)
  -particle roughness

Question 15

Fluid chracteristics include 1:

Answer 15

• density/viscosity

Question 16

Relative velocity chracteristics include 1:

Answer 16

• velocity of solid vs fluid

Question 17

After much research, the friction factor equation was observed by —— to be:

Answer 17

Moody

f = 4 (16 / Re)

Question 18

In a laminar flow, the shear stress is directly proportional to ——- ——-

Answer 18

viscous drag

Question 19

In a pipe with laminar flow, it is a —— —– relationship to the —— ——-

Answer 19

directly proportional, shear stress

Question 20

Pressure drop in a pipeline is directly proportional to ….

Answer 20

aspect ratio of the pipe

Question 21

Laminar flow theory states the relationship between the velocity and pipe radius is

Answer 21

V = Vmax ( 1 - r^2 / R^2)

Question 22

Darcy Weisbach equation is

Answer 22

ΔPL = f (L/D) (1/2) ρ (Vavg)^2

Pressure loss = friction factor X (aspect ratio of pipe) X (1/2) X density of fluid X (avg velocity)^2

Question 23

In a laminar flow, the friction factor is stated as

Answer 23

f = 64/Re

Question 24

Conservation of energy equation of a system

Answer 24

E sys / dt = W (per unit time) net in + Q (per unit time) net in

Question 25

CLOSED system momentum conservation equation

Answer 25

M1 v1i + M2 v2i = M1 v1f + M2 v2f

Question 26

Body forces are those that

Answer 26

act throughout the body of a fluid control volume

Question 27

Surface forces are those that

Answer 27

act on the control volume’s surface

Question 28

3 types of forces on fluid inside of a control volume

Answer 28

1) External body forces
2) Fluid-fluid surface forces
3) Fluid-solid contact forces

Question 29

Example of external body forces

Answer 29

• gravity
• magnetic

Question 30

Example of fluid-fluid surface forces

Answer 30

• pressure
• viscous forces

Question 31

Example of fluid-solid contact forces

Question 32

Rate of change of linear momentum conservation for a control volume is

Answer 32

d (m V)CV / dt = Σ F (applied on CV surface) + Σ (m V)in - Σ (m V)out

Question 33

How can this equation be split up into its individual components?

Σ F = m (V2 - V1) => ….

Answer 33

Σ Fx = m (V2x - V1x)
Σ Fy = m (V2y - V1y)
Σ Fz = m (V2z - V1z)

Question 34

What happens to atmospheric forces acting on a closed fluid control volume?

Answer 34

They can be ignored as they cancel out

As the forces apply on all surfaces of the control volume