Ghosh - 550Page 111/01/2018
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 requirespractice 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 . 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, strengthofmaterials 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.
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 byits 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 densityis 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 surfaceforces 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:
Properties
Based on
EMEM 415 Topics 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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