Exam 3

Question 1

Dimensional analysis is a _________-_______ method that uses the fact that any number or expression can be multiplied by one without changing its value

Answer 1

problem-solving

Question 2

dimensional analysis involves combining dimensional variables to form ______________ _______

Answer 2

dimensionless groups

Question 3

Dimensional analysis is useful in representing experimental data in a very ________ and __________ way

Answer 3

compact, efficient

Question 4

Dimensional analysis began with _______ in 1687

Answer 4

newton

Question 5

dimensionless groups are a combination of dimensional or dimensionless quantities having _____ overall dimension

Answer 5

zero

Question 6

Buckingham refered to the dimensionless groups as __, which is the reason the theorem is called the ___ theorem

Answer 6

pi, pi

Question 7

if an equation truly expresses a proper relationship between two variables in a physical process, it will be dimensionally ______________

Answer 7

homogeneous

Question 8

quantities that vary in the problem (pressure, velocity, elevation)

Answer 8

dimensional variables

Question 9

held constant during the study (gravity, density)

Answer 9

dimensional constants

Question 10

name 2 dimensional variables that are already dimensionless

Answer 10

angles and SG

Question 11

k is the number of ___________ dimensionless groups, n is the number of ________ involved, and m is the number of ______ dimensions included in the variables

Answer 11

independent, variables, basic

Question 12

Most dimensionless numbers show a comparison of the ______ that are governing the fluid __________

Answer 12

forces, behavior

Question 13

kinetic force are the forces associated with fluid motion, it is also _________ ______

Answer 13

inertial force

Question 14

__________ _______ is the ratio of inertial forces to viscous forces

Answer 14

Reynold’s number

Question 15

Reynolds number is a convenient parameter for predicting if a flow condition will be ________ or _________

Answer 15

laminar, turbulent

Question 16

_____ ________ is an indicator of how important compressibility effects are in a fluid flow

Answer 16

mach number

Question 17

if mach number is ______ then the kinetic force associated with the fluid motion does not cause a significant density change and the flow can be treated as impressible

Answer 17

small

Question 18

if the mach number is ______ there are often appreciable density changes that must be considered in model studies

Answer 18

large

Question 19

an _________ ______ is a shock that the flow encounters at some angle

Answer 19

oblique shock

Question 20

the ______ ________ is an important parameter in liquid atomization

Answer 20

weber number

Question 21

Weber Number
The ________ _________ of the liquid at the surface of a droplet is responsible for maintain the droplet’s shape

Answer 21

surface tension

Question 22

If a droplet is subjected to an air jet and there is a
relative velocity between the droplet and the gas, _______ ______ due to this relative velocity cause the droplet to
deform.

Answer 22

kinetic forces

Question 23

If the Weber number is too large, the kinetic force ____________ the surface-tension force to the point that the droplet shatters into even _________ droplets.

Answer 23

overcomes, smaller

Question 24

• The __________ number is an important parameter for flows
  with a repetitive frequency (oscillating flows).

Answer 24

strouhal

Question 25

__________ is the theory and art of predicting prototype performance from model observations.

Answer 25

similitude

Question 26

The basic and perhaps the most obvious requirement is that the model be an ______ geometric _______ of the prototype.

Answer 26

exact, replica

Question 27

All linear dimensions must bear the same ratio between the model and prototype. * This is called ___________ similitude.

Answer 27

geometric

Question 28

The other basic requirement in similitude is that the forces that act on corresponding masses in the prototype and model must have the same ratio throughout the entire flow field. * This is called _________ Similitude

Answer 28

dynamic

Question 29

Since the forces acting on the fluid elements control the motion of those elements, it follows that _________ similarity will yield similarity of flow _________

Answer 29

dynamic, patterns

Question 30

Dynamic Similitude is achieved by making the __________ of the significant dimensionless groups 𝑅𝑒, 𝑀𝑎, 𝐶𝑝, 𝑒𝑡𝑐. for the model flow ______ (or the same) for the prototype flow

Answer 30

magnitude, equal

Question 31

_________ flow and _________ flow are classified as exact solutions.

Answer 31

Couette, Poiseuille

Question 32

Three cases will be discussed, each with different boundary conditions * Case 1: _______ Flow * Case 2: ____Reynolds Number Film Flow Down an Inclined Surface * Case 3: _________ Flow Between Stationary Parallel Plates

Answer 32

Couette, Low ,Poiseuille

Question 33

the exact solution to Couette flow is a ______ velocity proflie

Answer 33

linear

Question 34

Poiseuille flow refers to a ________ flow in a conduit, The conduit considered is a rectangular channel. * A channel is a flow passage between ____ parallel plates

Answer 34

laminar, two

Question 35

Experiments have revealed that the flow in a rectangular channel will be laminar for a Reynolds number below _____

Answer 35

1000

Question 36

the exact solution in Poiseuille is a _________ shape and the velocity profile is a function of y^2

Answer 36

parabolic

Question 37

The central idea of the boundary layer concept is to _________ the flow near the surface of a body as a thin layer that is _________ from the surrounding flow.

Answer 37

idealize, distinct