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Chem / Physics II > Flow ppt notes > Flashcards

Flow ppt notes Flashcards

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1
Q

what are a matter that continuously changes shape when subjected to shear force (tangential force?

A

Fluids

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2
Q

What are not fluids as they resist shape changes, when their shape is changed they maintain that changed shape

A

Solid

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3
Q

With FLUIDS the stress is proportional to the what?? in r/t to hydrostactics

A

Rate of change

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4
Q

with SOLIDS stress is proportional to the what? in r/t hydrostatics?

A

change in shape

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5
Q

*************************************************

Are liquids and gasses both fluids?

A

Yes

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6
Q

*****************************************

what is the big difference between fluids (liq/gas) and solids?

A

Solids don’t change

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7
Q

what is perpendicular forces (normal forces)?

A

force applied perpendicular to surface

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8
Q

fluids are matter that respond in one of two ways to normal forces (perpendicular forces).

how do liquids respond?

how do gasses respons?

A

liquids- resistance to compression , minimal volume changes.

Gasses- compressible and easily expandable

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9
Q

equation for force?

A

F=ma

force= mass X acceleration

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10
Q

what are the 3 forces associated with fluids

A
  1. gravity
  2. pressure
  3. friction
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11
Q

pressure forces are the result of differences in pressure from one point to another. this is also called the what?

A

Pressure Gradient

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12
Q

friction is proportional to what?

A

viscosity

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13
Q

what is the physical property of a fluid that relates shear stress to rate of strain?

A

viscosity

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14
Q

what is the measure of resistance to flow?

A

viscosity

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15
Q

what is the quanity of a fluid passing a point per unit of time?

A

flow

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16
Q

*************************************

equation for flow.

give example of how flow is written

A

F=Q/t

F= mean flow

Q= Quanity

t= time

eg- L/min

mL/hr

etc

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17
Q

*********************************

what type of flow is smooth flow free of eddies or turbulance, streamlined

A

Laminar flow

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18
Q

*******************************

with laminar flow, the flow _______________ is the greatest being about twice the mean flow.

A

in the center

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19
Q

*****************************

with laminar flow the flow along the walls of the tube is near what?

A

zero

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20
Q

just to listen for a basic understanding about flow

A

your on a boat on the sSt. johns river and just cruising along,(lamina the tide is moving and your just cruisin along, thn you get to down town, and the river narrows (by main street bridge) the watr is jst churning little whirl pools and etc. that is now turbulent

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21
Q

this a picture of laminar flow notice that the flow in the center is the greatest

A
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22
Q

*************************************

laminar (streamlined) flow is described mathmatically by who’s law?

A

Pouiseuille’s law

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23
Q

*********************

what is the formula for Pouiseuille’s law

A

π=pie 3.14

r= radius

xP= pressure gradient

n= viscosity

l= length

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24
Q

*****************************

With Pouiseuille’s law, what 2 thigs are directly proportional

A

radius4

pressure gradient

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25
Q

with Pouiseuille’s law F is directly proportional to the fourth power of the radius. what does this mean in laymen terms

A

flow through a larger bore needle is faster than a small one

26
Q

With Pouiseuille’s law F is directly proportional to the hydrostatic pressure gradient, what does this mean in laymen terms?

A

raising the IV pole increases hydrostatic pressure in fluid delivered to a pt by gravity, flow iincreases proportionally

27
Q

****************************

with Pouiseuille’s law what 2 things are inverly proportional to flow

A

fluid viscosity

length

28
Q

With Pouiseuille’s law give an example of how viscosity is inversly proportional to flow

A

polycythemic pts have higher blood viscosity, flow reduced

Anemic pt’s have low viscosity, so flow increased

29
Q

With Pouiseuille’s law give an example in laymen terms how length is inversly proportional to flow

A

reducing the length of a needle inclreases flow from an IV bag

30
Q

************************************

With Pouiseuille’s law which factor is the most sensitive to change that will effect flow the most!!!!!

and why?

this will be a test question

A

Radius

double the radius= increase in flow x 16

Half the radius= decrease flow t0 1/16th

ex 24=16

14= 1

31
Q

with laminar flow

flow is directly proportional to what besides radius

A

Pressure

ex in Pouiseuille’s law the change in pressure gradient

the higher the pressure the greater the flow (raise the IV bag)

32
Q

what is teh equation for resistance

A

R= P/Q

R= resistance

P= pressure

Q= flow

33
Q

flow is _______ propartion to viscosity r/t Pouiseuille’s law

A

inveresly

34
Q

Blood viscosity increases with what factors

A

Low temp

increase in age

cigarette smoking

Increased Hct

Abnormal plasma levels

35
Q

********

what is the BIGGEST factor that increases blood viscosity thus decreasing flow

A

Increasing Hct

36
Q

According to Pouiseuille’s law length is _________ proporionate to flow

A

Inversely

37
Q

With Pouiseuille’s law and its relationship to length. decreasing the length by 1/2 results in flow that is _________ the original volume?

and thus if you double the length you ______ the flow

A

Twice

Half

(1/2 length u double the flow, you double the length you 1/2 the flow, yes this is a large factor but remember the largest factor that affects flow remain the radius which has a 16 fold increase if u double it)

38
Q

A recap of all learned

Flow is directly proportional to ______

Flow is directly proportional to ______

Flow is inversely proportional to ______

Flow is inversely proportional to ______

A

Radius4

change in pressure

viscosity

length

39
Q

don’t memorize just remember the formula for resistance and what effects it.

so what is the formula for resistance

A

R=P/F

R=resistance

P=change in pressure

F= flow

or basically

P1-P2/ flow (Q)= R

40
Q

what is the equation for resistance with laminar flow?

A

R= (8nL) / (πr4)

so

R=resistance

8n= viscosity

L=length

π= 3.14

r= radius4

41
Q

***********************

so what effects resistance

resistance is Inversly proportional to ____

And directly proportional to __________ and _______

A

Inversely-r4 ( basically the greater the radius, the smaller the resistance)

Directly- viscosity (greater blood viscosity, greater resistance)

Directly- Length (longer the tubem the greater the resistance)

***basiclly the oposite of flow, b/c resistance is what opposes flow

R= (8nL) / (πr4)

42
Q

What type of flow contains irregular swirls or eddies?

A

turbulent

43
Q

*****************************

what measures the propensity for turbulent flow

A

Reynolds number

44
Q

how is reynolds number calculated

A

(v p d) / n l

V= velocity

p= density

d= diameter

n= viscosity

l= length

45
Q

********************************

what reynolds number = turbulent flow?

what #= laminar flow?

A

turbulent > 2000

laminar < 2000

46
Q

what is the critical velocity r/t reynolds number

A

is the velocity of a gas at which Re= 2000 and laminar flow converts to turbulent

47
Q

with pouiseuille’s law at low flows ________ predominates

and at high flows _______ predominates

A

viscosity

density

ex. a decrease in DENSITY will result in an increase in FLOW

48
Q

Water is more dense than air, greater the water content of the air the more ______ the air is

A

Viscous

49
Q

iin the smaller bronchials flow is slowed and becomes or is maintained as what type of flow?

A

laminar

50
Q

what is the flow like in the upper larger bronchus of the airway

A

turbulent

51
Q

flow becomes turbulent if what occurs (in a clinical presentation)

A

velocity of flow is high

tube wall is narrow

kinks, bends, narrowing, branches of tube

fluids flow through and orfice

52
Q

****************************

what is Bernoulli’s principle

A

with flow through a constricted tube, the velocity of flow increases and the lateral pressure on the walls of the tube decreases

ok so basically when something gets smaller speed increases and pressure is aimed at the end of the tube more than on the walls.. not as hard as he states to understand.

to have an example if u let water gtt out of a hose it is wide spread and flows slow, if i place my finger on the end the speed (velocity) increases and the flow is more forward and straight than spread out.

53
Q

**************************************

know the difference b/t venturi effect and Bernoulli’s principle

A

the Bernoulli’s principle explains the verterni effect

54
Q

********

when fluid flows through a constricted region of a tube (venturi tube) the velocity of flow increases, and the lateral pressure on the walls decrease. is what principle?

A

Bernoulli’s principle aka the bernoulli effect

55
Q

***********************

what is the venturi effect

A

with flow though a constricted tube that has an opening at the constriction air entrainment will occur owing to the decreased pressure at the constriction (as descriped by the bernoulli’s effect)

basically b/c if the bernoulli’s principle is u place a hole there a venturi effect will occur (which is simply the allowing of air in due to the increased velocity and decreased wall pressure)

56
Q

What is another effect r/t Bernoulli’s principle that causes a stream of flow to be held along one side of a tubes wall at a bifurcation of wider bore than the preceding constriction

A

Coanda effect

57
Q

The coanda effect may explain what 2 things in the body

A
  • how gas is misdistributed at the alveolar level
  • how some MI occur dispite lack of total occlusion of the vessel
58
Q

what is the fluid logic utilizing the Coanda effect?

A

it’s the creation of a valve mechanism consisting of tubes for flow administration at the site of the constriction’s outlet, so that the flow can reach the other branch

(this is being used in smaller portable ventilators as bellows or not required***for knowledge)

59
Q

Which liter NS IV bag would flow faster?

one infusing through a 20 cm (8 inch) #16g central line or a PIV #20g 1 inch angiocath (assuming the 16g is twice the diameter of a #20)

do the math out

A

the 16g central line

dispite the 7 inches of length difference

the doubled radius is more important than the length

60
Q

which liter of NS IV bag would flow faster, one infusing through a 40cm 16inch #16G PA cath or a periphreal #20G 0.5 inch angiocath (assuming a 16g is twice the diameter)

A

the 20g wins

although the radius is doubled the length is such a differnce that the 20g will give better flow

61
Q

give examples of the venturi effect in clinical situations

A
  • with the bellow they are pnuematic driven and as the compress the venturi effect allows air to enter so that not only O2 is being used
  • TTJV- pushing the air in causes air to enter the oropharynx as well
62
Q

with Pouiseuille’s law what are the 3 variable parts of the equation, all others are constants

A

R

change is pressure

length

(side note n is constant per fluid type)

Chem / Physics II (20 decks)

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