Bruce's Fluid Dynamics Final Prep

Question 1

Pressure definition ?

Answer 1

the force per unit area applied in a direction perpendicular to the surface of an object

Question 2

Hydrostatic pressure

Answer 2

(AKA: Stagnation Pressure) The pressure at any given point of a non-moving fluid

Question 3

what do we measure with our manometers ?

Answer 3

Static Pressure

Question 4

Hydrostatic Pressure - Static Pressure =

Answer 4

Dynamic Pressure

Question 5

‘Where the velocity of the fluid is high

Answer 5

the (static) pressure is low’

Question 6

Static Pressure + dynamic pressure =

Answer 6

Total Pressure

Question 7

Bernoulli’s Priciple =

Answer 7

P+1/2pv^2 = Po
P=static pressure
p=density of the fluid
v=flow velocity
Po=total pressure

Question 8

Velocity is directly related to ?

Answer 8

=Flow

and inversely related to cross sectional area.

Question 9

Boundary layers are slower in ?

Answer 9

the edge

Question 10

Boundary layers are faster in ?

Answer 10

the middle

Question 11

3 types of fluid flow in pipes ?

Answer 11

• laminar
• turbulent
• transient

Question 12

Laminar Flow =

Answer 12

happens when dealing with small pipes and low flow velocities

Question 13

Turbulent Flow =

Answer 13

• vortices, eddies and wakes make the flow unpredictable

- happens in general at high flow rates and with larger pipes

Question 14

Transitional Flow =

Answer 14

mixture of laminar and turbulent flow, with turbulence in the center of the pipe, and laminar flow near the edges

Question 15

Transient flow range =

Answer 15

2300 < 4000

Question 16

Laminar Flow range =

Answer 16

RE < 2300

Question 17

Turbulent flow range =

Answer 17

RE > 4000

Question 18

Reynolds number (Formula) =

Answer 18

Re =
(velocity)(radius)(density)
_____________________
Viscocity

Question 19

Poiseuille’s law on blood circulation in the body is dependent on what?

Answer 19

Laminar flow

Question 20

In turbulent flow the flow rate is proportional to the

Answer 20

square root of the pressure gradient

Question 21

atheroma = turbulent flow

Answer 21

is an accumulation of degenerative material in the tunica intima (inner layer) of artery walls.

Question 22

Rapid changes in vessel diameter may lead to what?

Answer 22

Turbulent flow

Question 23

As the blood leaves the arterial cannula, it is ____ flow?

Answer 23

Turbulent

Question 24

Poiseuille’s Law:

Answer 24

Delta P =8u L Q / pi r^4

Delta P = pressure loss
L = length of pipe
u = dynamic viscosity
Q = volumetric flow rate
r = radius
d = diameter
pi  = mathematical constant Pi

Question 25

As length increases. .

Answer 25

-Resistance Increases
-Flow decreases
for a given pressure

Question 26

As radius increases. .

Answer 26

-Resistance decreases
-Flow increases
for a given pressure

Question 27

which oxygenator circuit has a lower resistance ?

series or parallel?

Answer 27

parallel

Question 28

Two variable that we manipulate that alter blood viscosity:

Answer 28

1-Temperature

2-Hematocrit

Question 29

Viscosity definition ?

Answer 29

a measure of the resistance of a fluid which is being deformed by either shear or tensile stress

Question 30

water is “thin”, having a ?

Answer 30

lower viscosity

Question 31

honey is “thick”, having a

Answer 31

higher viscosity

Question 32

the less viscous the fluid is, the . . . .

Answer 32

greater its ease of movement (fluidity).

Question 33

State the units of viscosity

Answer 33

Viscosity centipoise (cP)

Question 34

Sheer stress is directly proportional to . . .

Answer 34

viscosity

Question 35

Sheer stress is inversely proportional to . . ..

Answer 35

the distance from the wall

Question 36

Newtonian fluids have

Answer 36

a constant viscosity

Question 37

Thixotropic fluids become

Answer 37

less viscus as the sheer force increases

Question 38

Thixotropy definition

Answer 38

property of certain gels or fluids that are thick (viscous) under normal conditions, but flow (become thin, less viscous) over time when shaken, agitated, or otherwise stressed.

Question 39

A thixotropic fluid displays a decrease in viscosity

Answer 39

over time at a constant shear rate.

Question 40

A shear thinning fluid displays decreasing viscosity with

Answer 40

increasing shear rate.

Question 41

anti-thixotropic causes:

Answer 41

causes an increase in viscosity or even solidification when exposed to constant shear stress for a period of time.
This property is called = rheopectic

Question 42

Blood is often referred to as Non-Newtonian but the most appropriate term would be ?

Answer 42

Thixotropic

Question 43

Smaller capillaires have greater sheer forces, what happens to the blood?

Answer 43

becomes less viscous

Question 44

Roller pumps have what 3 qualities ?

Answer 44

• Positive displacement
• resistance independent
• predictable flow output

Question 45

1/4” tubing =

Answer 45

13 ml/revolution

Question 46

3/8” tubing =

Answer 46

27 ml/revolution

Question 47

1/2” tubing =

Answer 47

44 ml/revolution

Question 48

Centrifugal pumps =

Answer 48

Preload and afterload dependent

Question 49

The Afterload of the centrifugal pump is determined by

Answer 49

everything down stream from it in the circuit:

• oxygenator,
• arterial filter
• size / length of the arterial line
• arterial cannula
• patient.

Question 50

During Vacuum Assisted Venous Drainage (VAVD) the preload is determined by

Answer 50

the amount of suction in the venous reservoir

Question 51

greater negative pressures reducing preload to the pump and thereby

Answer 51

reducing blood flow.

Question 52

Safety features of centrifugal pumps

Answer 52

• Cannot generate extreme pressures
• ## deprime when challenged with large bolus of air.