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Transport Phenomena
Overview
This digital textbook was designed to assist students in the course EMEM 550 Transport Phenomena. The course was first introduced in 1986 as a substitute for
EMEM 516 - Fluid Mechanics II. This course is the second course in a two-course
sequence in Fluid Mechanics offered in the core curriculum in Mechanical
Engineering at Rochester Institute of Technology.
The course notes are presented in a concise fashion with all mathematical details.
This is meant to be a supplement, and not a substitute, to the lecture material. A
mathematically oriented subject such as Transport Phenomena requires practice of
plenty of problems to develop a full understanding of the detailed structure of fluid
flows. The assigned problems in classroom must be solved in a systematic and timely
fashion to excel in test-taking in this course. The topics and concepts are linked.
The reader should have Microsoft Word 97 (or later) and a CD-ROM drive
installed in the personal computer to access these notes. The files are presented as
Read-only to prevent accidental deletion. In addition, some entertainment media are
provided. While studying, the reader can play some background music of his or her
choice from the CD-ROM or, using compressed Real Audio files. Please install this
program first in a directory (path c:\windows\desktop\transport) and then copy the
music files into this directory to enjoy this feature. The notes can be printed from
within Word 97 or, using the Document Printer. There is a site map provided on the
cover page with the button Course Contents.
[Note to students: Care was taken to provide accuracy in the printed information.
However there may be some errors that were missed due to the limited time in this
project. Please report these to me in class, or send e-mail to angeme@rit.edu. A.G.]
Prerequisites
This class is the second course in fluid flow theory offered by the department of
mechanical engineering at Rochester Institute of Technology. Students registering in
the course must have completed the course EMEM 415 - Fluid Mechanics. It is
assumed that the readers of these notes have a good background of statics,
dynamics, strength of materials and thermodynamics. The emphasis in this course is
on the differential analysis of fluid motion rather than the control volume approach,
which is the primary focus of EMEM 415.
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What is Fluid Mechanics?
Fluid mechanics is a branch of physics, which involves the study of properties and
behavior of a typical liquid or gaseous substance, commonly called a fluid. Although
fluids do not normally exist in a solid state some substances (e.g., coal tar, glass, etc.)
may exist both in fluid and solid states under certain conditions. Therefore we shall
define a fluid substance not by its appearance but by its functionality.
While we learn about fluids, which are clear, often invisible substances, it is more
appropriate to compare their properties to solids, which are clearly visible and may
be easier to study. Although several properties of a fluid are similar to those of a
solid, there is one fundamental difference between a fluid and a solid. A fluid will
deform continuously under an applied shear load, no matter how small it is. This
property is quite different for a solid, which usually resist shear loads and will fail
only if the loads are excessive.
Let us recall the relationship between stress and strain from an earlier course on
strength of materials. When a solid is subjected to a shear stress it usually develops
an internal shear strain, given by the Hooke’s law. The constant of proportionality
is called the shear modulus. In the case of fluids, which deform continuously, the
shear stress is usually proportional to the rate of shear strain. The class of fluids
exhibiting this property is called the Newtonian fluids, named after Sir Isaac
Newton. Most common fluids fall under this category, which will be our primary
focus of study in this class. The constant of proportionality between the shear stress
and the rate of shear strain is called the absolute viscosity, or dynamic viscosity, .
Another property related to the dynamic viscosity is called the kinematic viscosity,
, which may be obtained by dividing the dynamic viscosity by the density of a fluid,
.
Now let us recall some concepts related to the density of a fluid. The term density is
equated to the mass per unit volume of a fluid substance. If we divide the density of
a fluid by the density of water, we can obtain the specific gravity of a fluid. You may
recall these and other concepts of pressure, body and surface forces as related to a
fluid from the first course on fluid mechanics (EMEM 415). We need to review these
as and when we get into problem solving in these pages. However, these are topics of
fluid statics that are not in our primary focus in this class. There are some fluid
dynamics topics from EMEM 415 which will be necessary for you to recall for the
understanding of the basics in this course. These will be revisited as necessary.
The realm of fluid mechanics study can be summarized by the flow chart
given on the next page:
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Fluid Mechanics
Fluid Statics
Fluid Dynamics
Properties
Based on
- Density
- Viscosity
- Pressure
- Buoyancy
- Surface
Tension
Incompressible Flows*
Compressible Flows*
( = constant)
Subsonic*
Transonic
M<1
M1
Irrotational Flows*
Inviscid Flows*
Pascal's
Laws
Archimedes'
Principle
EMEM 415 Topics
( = 0)
Hypersonic
M>5
Rotational Flows*
(= 0)
- Barometry
- Manometry
- Pressure on
Submerged
Surfaces
- Floating
Objects
Supersonic
M>1
Viscous Flows*
Laminar Flows*
Turbulent Flows*
EMEM 550 Topics
* These are the major topics of the course Transport Phenomena. There is not
enough time in the course to cover details of the compressible flows. Only subsonic
flows will receive the focus. There are other courses like EMEM 838 - Ideal Flows,
or, EMEM 675 - Aerodynamics that cover details in this area. Likewise, rotational
flows and turbulent flows will receive only limited exposure.
To summarize, this digital textbook provides you a complete and compact set of
notes with example problems and all necessary concepts to master the material.
Please use these notes to supplement your own notes taken from class discussions.
Study these procedures and practice them as often as you need. Some background
information necessary to review is provided next.
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