Chapter 6

Question 1

What is the difference between a local convection heat transfer coefficient and an average heat transfer coefficient?

Question 2

What are the units for local and average heat transfer coefficients?

Question 3

What are the forms of Newton’s law of cooling for a heat flux and a heat rate? What are the analogous forms for convection mass transfer, expressed in molar and mass units?

Question 4

Provide some examples for which species transfer by convection is pertinent

Question 5

What is Fick’s Law?

Question 6

What is the velocity boundary layer and under what conditions does it develop?

Question 7

What is the thermal boundary layer and under what conditions does it develop?

Question 8

What is the concentration boundary layer and under what conditions does it develop?

Question 9

What quantities change with location in a velocity boundary layer?

Question 10

What quantities change with location in a thermal boundary layer?

Question 11

What quantities change with location in a concentration boundary layer?

Question 12

Recognizing that convection heat (mass) transfer is strongly influenced by conditions associated with fluid flow over a surface, how is it that we may determine the convection heat (species) flux by applying Fourier’s (Fick’s) law to the fluid at the surface?

Question 13

Do we expect heat and mass transfer to change with transition from a laminar to a turbulent boundary layer? If so, how?

Question 14

What laws of nature are embodied by the convection transfer equations?

Question 15

What physical processes are represented by the terms of the x-momentum equation (6.28)?

Question 16

What physical processes are represented by the terms of the x-momentum equation (6.29)?

Question 17

What physical processes are represented by the terms of the x-momentum equation (6.30)?

Question 18

What special approximations may be made for conditions within thin velocity boundary layers?

Question 19

What special approximations may be made for conditions within thin thermal boundary layers?

Question 20

What special approximations may be made for conditions within thin concentration boundary layers?

Question 21

How is the Reynold’s number defined?

Question 22

What is the Reynold’s number’s physical interpretation?

Question 23

What role is played by the critical Reynold’s number?

Question 24

What is the definition of the Prandtl number?

Question 25

How does the Prandtl number’s value affect relative growth of the velocity and thermal boundary layers for laminar flow over a surface?

Question 26

What are representative room-temperature values of the Prandtl number for a liquid metal, a gas, water, and an oil?

Question 27

What is the definition of the Schmidt number?

Question 28

What is the physical interpretation of the Schmidt number?

Question 29

How does the Schmidt number influence the relative velocity, thermal, and concentration boundary layer development for laminar flow over a surface?

Question 30

What is the definition of the Lewis number?

Question 31

What is the Lewis number’s physical interpretation?

Question 32

How does the Lewis number influence the relative velocity, thermal, and concentration boundary layer development for laminar flow over a surface?

Question 33

What is the coefficient of friction?

Question 34

For flow over a prescribed geometry, what are the independent parameters that determine local and average friction coefficient values?

Question 35

What is the Nusselt number?

Question 36

For flow over a prescribed geometry, what are the independent parameters that determine local and average Nusselt number values?

Question 37

What is the Sherwood number?

Question 38

For flow over a prescribed geometry, what are the independent parameters that determine local and average Sherwood number values?

Question 39

Under what conditions may velocity, thermal, and concentration boundary layers be termed analogous? What is the physical basis of analogous behavior?

Question 40

What important boundary layer parameters are linked by the heat and mass transfer analogy?

Question 41

What is the physical basis of the evaporative cooling effect? Have you ever experienced the effect?

Question 42

What important boundary layer parameters are linked by the Reynolds analogy?