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Heat and Flow 4 > Quiz > Flashcards

Quiz Flashcards

1
Q

The Conservation of mass (continuity) equation may be derived from the GENERAL TRANSPORT EQUATION by setting the transport variable, phi, and source term, S respectively

A

phi = 1

S= 0

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2
Q

In Fick’s law of diffusion the units of the diffusion coefficient are:

A

m^2/s

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3
Q

In an non-Newtonian fluid the shear stress is directly proportional to:

A

The Strain rate to the power of an exponent not equal to 1

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4
Q

In the Energy Equation the term responsible for viscous heating is often called:

A

The dissipation function

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5
Q

An example of a TRUE SOURCE TERM in the energy equation is:

A

Nuclear Fission

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6
Q

In the derivation of the Energy Equation the RATE OF WORK acting on the control volume surface may be express as the product of:

A

Force and Velocity

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7
Q

A model of the flow which considers a fluid element fixed in space

A

Eulerian

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8
Q

An example of a CONSTITUTIVE RELATIONSHIP is

A

Stokes hypothesis

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9
Q

The constant of proportionality in Fick’s law of Diffusion is

A

The mass diffusivity

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10
Q

The following term

duu/dx

can be used to describe

A

The convection of acceleration

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11
Q

A definition of fully developed, laminar pipe flow is as follows:

A

All axial gradients are zero except the pressure gradient

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12
Q

In the General Transport Equation the operator GRAD does the following

A

Converts a scalar to a vector

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13
Q

In the Navier-Stokes equation, a NORMAL STRESS term contains the following (where the symbols have their usual meaning)

A

du/dx

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14
Q

What does the following term represent?

mu/rho (d^2u/dx^2)

A

The diffusion of u in the x direction for constant viscosity

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15
Q

The Stokes’ relatioship for shear stress and strain-rate may be express as

txy = tyx = mu(du/dy+dv/dx)

The equality:

txy = tyx

Is true because of:

A

Conservation of angular momentum

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16
Q

Fourier’s law of conduction may be express as:

q = - kA(dT/dx)

Where the negative sign is necessary in order to

A

Ensure that the 2nd law of thermodynamics is upheld.

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17
Q

The GENERAL TRANSPORT EQUATION consists of the following terms:

A

Transient + Convection + Diffusion + Source

TRANny CONVicts DIe SOURly

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18
Q

An example of a non-Newtonian fluid is:

A

Blood

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19
Q

∇.u = 0

may be expanded into what form?

A

du/dx + dv/dy + dw/dz = 0

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20
Q

∇.u = 0

Describes what?

A

The steady state continuity equation for incompressible flow

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21
Q

An example of a Newtonian fluid is

A

Water, Air, Alcohol, Milk, Glycerol, Thin Motor Oil

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22
Q

Define Newtonian Fluid

A

A fluid that all viscous stresses arising in the flow are, at all points, linear to the local strain rate and rate of change of its deformation over time.

23
Q

In the GENERAL TRANSPORT EQUATION what does phi mean?

A

Mass, Momentum, Energy, Species Concentration.

MASSive MOMENTs ENERGise SPECky Cunts

24
Q

What does the transient terms in GTE mean?

A

Accumulation Rate of the variable, phi.

Can be expressed in terms of Convection, diffusion and source terms.

25
Q

What does The Convection Terms in GTE depend on?

A

Convection Term only becomes important when the variables in partial derivatives vary in direction

26
Q

Convection Terms as “equations” are:

A

d(rho*u^2)/dx

d(rhovu)/dy

d(rhoue)/dx

27
Q

Diffusion process is characterised by a dependency on what?

A

a gradient of a particulat variable and occurs at a molecular level.

28
Q

State Fourier’s Law of Heat Conduction.

A

q = -k (dT/dx)

29
Q

What does phi represent in the energy equation?

A

Dissapation function

30
Q

Why is the dissipation function important in compressible flows?

A

Contributes significant viscous heating of fluid

31
Q

Where does viscous heating also occur?

A

Incompressible flows, lubrication of bearings and journals

32
Q

What units does species, M have?

A

kg substance/ kg mixture

KgA/Kg(A+B

33
Q

Is species concentration scalar or vector?

A

Scalar

34
Q

what four terms make up the species concentration equation?

A

transient, convection, diffusion, source

TRANny CONVicts Die SOURly

35
Q

What is an example of a constitutive or particular relationship?

A

Stoke’s hypothesis

36
Q

What is Fick’s Law of diffusion?

A

Thermal energy diffusing from high concentration regions to low concentration regions.

37
Q

What can a species be quantified in terms of?

A

Mass density and molar concentration.

38
Q

What are the units for mass density and molar concentration?

A

kg/m^3 and Kmol/m^3

39
Q

what is the relationship between mass density, molar concentration and molar mass?

A

phi i = Mi * ci

40
Q

What are the units of the diffusion coefficient?

A

m^2/s

41
Q

What are the units of volumetric source (na) of phi A

A

kg/s/m^3

42
Q

What is heat transfer?

A

Heat transfer is thermal energy in transit- as a result of temperature differences

43
Q

What is momentum transfer?

A

Acceleration or deceleration of fluid particles as a result of motive or retardive forces.

44
Q

What is mass transfer?

A

Mass transfer is mass in transit as a result of concentration differences?

45
Q

Phase change example?

A

Water evaporating: Energy is taken from the water droplet (cooling) allowing it to break liquid bond, this energy turns into laten heat as the liquid into a gas, this energy is released as the gas is condensed back into a liquid

46
Q

Is the model Eularian or Lagrangian?

A

Eulerian: Fixed in space

Lagrangian: Moves in space

(abcdEFg…LMnop…)

47
Q

delta phi = ?

A

Net convection + net diffusion + source/sink +effects on CV surface (shear/normal stresses)

48
Q

What are the four physical fundamental principles?

A

Mass, Energy, Species Concentration, momentum

49
Q

What forces act on the CV to allow us to apply momentum equation?

A

Body forces (gravitational, magnetic)

Surface Forces ( Shear and normal stresses pushing and tugging).

50
Q

What type of diffusion occurs and what direction is it in when shear stress are present on 2d body?

A

Diffusion of momentum in the high to low shear direction (look for terms du/dy, dv/dx etc.)

51
Q

What does the term
u*du/dx
represent?

A

Convection of u in x direction

52
Q

What does the term
v*du/dy
represent?

A

Convection of u in the y direction

53
Q

What does the term
u/p(d^2u/dx^2)
represent?

A

Diffusion of u in the x direction due to normal stresses for constant velocity

54
Q

What does the term

u/p(d^2u/dy^2)

A

Diffusion of u in the y direction due to shear stresses for constant velocity.

Heat and Flow 4 (1 decks)

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