Chapter 4 - Fluid Dynamics

Question 1

***First bunch of cards are in Kinematics

Answer 1

Go to Kinematics

Question 2

What is fluid dynamics?

Answer 2

The study of fluids in motion

Question 3

What is viscosity (n)? Viscous drag?

Answer 3

Viscosity: the resistance of a fluid to flow

Increased viscosity of a fluid increases its viscous drag (non conservative force)

Pas = (Ns)/m^2

Question 4

What is laminar flow?

What equation is used for it?

Answer 4

Laminar: smooth, orderly ..think of an object sinking and how you would have parallel, smooth flow lines around it

*layers have different speed
*ei closer to wall of pipe is slower
Turbulent:

POISEUILLE’S LAW:

Q = (πr^∆P) / 8nL

Q = flow rate
r  = radius of tube
∆P = pressure gradient
n (eta) = viscosity
L = length of pipe

Question 5

What is turbulent flow?

Answer 5

Turbulent: rough and disorderly
*eddies!

Critical speed: speed of fluid, with unobstructed flow, when turbulence arises

Vc = (Nrn) / pD

D=diameter
Nr = Reynolds number
Vc = critical speed

Question 6

What’s the difference between flow rate and linear speed?>

Answer 6

Flow rate: volume per unit time (\
*constant for closed system

Linear speed: linear displacement of fluid particles in a given amount of time

Q = v1a1 = v2a2

Q= flow rate

V1, V2 = linear speeds

Question 7

What is Bernoulli’s equation?

Answer 7

P1 + .5pv1^2 + pgh1 = P2 + .5pv^2 +pgh2

P = absolute pressure

They need to balance out! Conservation of energy

• if P1 = P2 then PE and KE are inverse

Question 8

Venturi effect

Answer 8

As the tube narrows, linear speed increases causing pressure on walls to decrease

PE is the same so as KE increases P decreases