12.3 - Moving Fluids - Streamlines and Laminar Flow

Question 1

What do streamlines represent?

Answer 1

The velocity of a fluid at each point within it

Question 2

How are they drawn?

Answer 2

As arrowed lines that show the paths taken by small regions of the fluid

Question 3

What is laminar flow?

Answer 3

Flow where adjacent streamlines do not cross over

Question 4

What are the key characteristics of laminar flow?

Answer 4

No abrupt changes in speed or direction, the velocity at a point is constant

Question 5

What is turbulent flow?

Answer 5

Streamlines crossing over into each other, swirling around

Question 6

What are regions formed by turbulent flow called?

Answer 6

Vortices or eddy currents

Question 7

In a water pipe, when is there laminar flow, and when is there turbulent flow?

Answer 7

Laminar: Low rate of flow
Turbulence: Rate reaches a critical point

Question 8

What 4 things does the rate of flow depend on?

Answer 8

Speed of flow, the radius of the tube, density, and viscosity of the fluid

Question 9

Why is laminar flow important for:
Aircraft
Water tubes
Food industry

Answer 9

• Laminar flow is key for uplift on wings
• Efficiency is greatly increased with laminar flow
• Laminar flow reduces bubbles when pouring liquid foods that will harden

Question 10

What is the viscosity of a fluid linked to?

Answer 10

How sticky it is

Question 11

In physics, what is this referred to as?

Answer 11

Resistance to flow

Question 12

Name two fluids that have a high viscosity?

Answer 12

Syrup and engine oil

Question 13

Name two fluids with a low viscosity:

Answer 13

Water and petrol

Question 14

Are all gases viscous or not viscous?

Answer 14

Not viscous

Question 15

How is viscosity defined in terms of flow?

Answer 15

As the resistance between adjacent layers

Question 16

When a sphere moves through a fluid, its movement of the fluid relative to the sphere is ——

Answer 16

Laminar

Question 17

What do the fluid molecules do to the sphere?

Answer 17

Adhere to it and move along with it

Question 18

What does this create?

Answer 18

Viscous drag

Question 19

What law does this lead to?

Answer 19

Stokes’ Law

Question 20

What equation represents Stokes’ Law?

Answer 20

F = 6πηrv

Question 21

What is η representing, and what are its units?

Answer 21

Measures the resistance to flow of the fluid. Units are N s m-2, or Pa s

Question 22

When the sphere is falling, what three forces is it subjected to?

Answer 22

Upthrust, Viscous Drag, and Weight

Question 23

At terminal velocity, what can be said about the three forces?

Answer 23

W = U + F