Fox and McDonald's. INTRODUCTION. TO. FLUID. MECHANICS. EIGHTH .. Additional Text Topics: PDF files for these topics/sections are available only on the. Fox and McDonald's Introduction to Fluid Mechanics, 8th Edition .. Additional Text Topics: PDF files for these topics/sections are available only on the Web site. Introduction to Fluid Mechanics 6th Edition Fox, Mcdonald & Pritchard (Optimized ) - Free ebook download as PDF File .pdf) or read book online for free.
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Fluid Mechanics Fox and Mcdonalds 8th Edition - Download as PDF File .pdf), Text File .txt) or read online. Fluid Mechanics Fox and. Fox and McDonald Introduction to fluid mechanics 9th osakeya.info For educational purposes only please!. FLUID. MECHANICS. SIXTH EDITION. ROBERT W. FOX. Purdue Unive;ity. ALAN T. McDONALD. Purdue University. PHILIP J. PRITCHARD. Manhattan College.
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Get New Updates Email Alerts Enter your email address to subscribe this blog and receive notifications of new posts by email. Join With us. Today Updates. In the Eulerian method of description, the properties of a flow field are described as functions of space coordinates and time. We shall see in Chapter 2 that this method of description is a logical outgrowth of the assumption that fluids may be treated as continuous media.
It goes without saying that the answer must include units. Consequently, it is appropriate to present a brief review of dimensions and units. We refer to physical quantities such as length, time, mass, and temperature as dimensions. In terms of a particular system of dimensions, all measurable quantities are subdivided into two groups—primary quantities and secondary quantities.
We refer to a small group of dimensions from which all others can be formed as primary quantities, for which we set up arbitrary scales of measure. Secondary quantities are those quantities whose dimensions are expressible in terms of the dimensions of the primary quantities.
Units are the arbitrary names and magnitudes assigned to the primary dimensions adopted as standards for measurement. For example, the primary dimension of length may be measured in units of meters, feet, yards, or miles.
Systems of Dimensions Any valid equation that relates physical quantities must be dimensionally homogeneous; each term in the equation must have the same dimensions.
Try the Excel workbook for this problem for variations on this problem. Thus force and mass cannot both be selected as primary dimensions without introducing a constant of proportionality that has dimensions and units.
Length and time are primary dimensions in all dimensional systems in common use. In some sys- tems, mass is taken as a primary dimension. In others, force is selected as a primary dimension; a third system chooses both force and mass as primary dimensions. Thus we have three basic systems of dimen- sions, corresponding to the different ways of specifying the primary dimensions. In this case the constant of proportionality, gc not to be confused with g, the acceleration of gravity!
The numerical value of the constant of proportionality depends on the units of measure chosen for each of the primary quantities. Systems of Units There is more than one way to select the unit of measure for each primary dimension. We shall present only the more common engineering systems of units for each of the basic systems of dimensions. Table 1. Following the table is a brief description of each of them. More than 30 countries have declared it to be the only legally accepted system.
Conshohocken, PA: ASTM, The dimensions arose because we selected both force and mass as primary dimensions; the units and the numerical value are a conse- quence of our choices for the standards of measurement.
Since a force of 1 lbf accelerates 1 lbm at SI units and prefixes, together with other defined units and useful conversion factors, are on the inside cover of the book.
That is, each term in an equation, and obviously both sides of the equation, should be reducible to the same dimensions. Almost all equations you are likely to encounter will be dimensionally consistent.
This problem involves unit conversions and use of the equation relating weight and mass: The student may feel this example involves a lot of unnecessary calculation details e.
The value of this constant depends on the surface condition of the channel. Unfortunately, the equation is dimensionally inconsistent!
A second type of problem is one in which the dimensions of an equation are consistent but use of units is not. However, it is used, in a sense, incorrectly, because the units traditionally used in it are not consistent.
For example, a good EER value is 10, which would appear to imply you receive, say, 10 kW of cooling for each 1 kW of electrical power. The EER, as used, is an everyday, inconsistent unit version of the coefficient of performance, COP, studied in thermodynamics. The two examples above illustrate the dangers in using certain equations. Almost all the equations encountered in this text will be dimensionally consistent, but you should be aware of the occasional troublesome equation you will encounter in your engineering studies.
As a final note on units, we stated earlier that we will use SI and BG units in this text. You will become very familiar with their use through using this text but should be aware that many of the units used, although they are scientifically and engineering-wise correct, are nevertheless not units you will use in everyday activities, and vice versa; we do not recommend asking your grocer to give you, say, 22 newtons, or 0.
SI units and prefixes, other defined units, and useful conversions are given on the inside of the book cover. Because it is difficult to precisely measure the filling of a container in a rapid production process, a fl-oz container may actually contain The manufacturer is never supposed to supply less than the specified amount; and it will reduce profits if it is unnecessarily generous.
Similarly, the supplier of components for the interior of a car must satisfy minimum and maximum dimensions each component has what are called tolerances so that the final appearance of the interior is visually appealing. Engineers performing experiments must measure not just data but also the uncertainties in their measurements. They must also somehow determine how these uncertainties affect the uncertainty in the final result. All of these examples illustrate the importance of experimental uncertainty, that is, the study of uncertainties in measurements and their effect on overall results.
There is always a trade-off in exper- imental work or in manufacturing: We can reduce the uncertainties to a desired level, but the smaller the uncertainty the more precise the measurement or experiment , the more expensive the procedure will be.
Furthermore, in a complex manufacture or experiment, it is not always easy to see which measurement uncertainty has the biggest influence on the final outcome.
Anyone involved in manufacturing, or in experimental work, should understand experimental uncertainties. Appendix E has details on this topic; there is a selection of problems on this topic at the end of this chapter. Basic Equations 1.
Explain and give examples. Methods of Analysis 1. Explain the mechanisms responsible for the temperature increase.
Consider a particle of net weight W dropped in a fluid. Determine the time required for the par- ticle to accelerate from rest to 95 percent of its terminal speed, Vt, in terms of k, W, and g.
The particles must drop at least 10 in. Find the diameter d of droplets required for this. The terminal speed of the particles is measured to be 0: Find the value of the constant k. Find the time required to reach 99 percent of terminal speed. What is its specific volume?
What are these values if the air is then com- pressed isentropically to psia? Plot the distance traveled as a function of time. Determine the maximum speed of free fall for the sky diver and the speed reached after m of fall. Plot the speed of the sky diver as a function of time and as a function of distance fallen. In the hands of a skilled archer, the longbow was reputed to be accurate at ranges to m or more.
Plot the required release speed and angle as a function of height h. Dimensions and Units 1.
What are the values in SI and EE units? Find the liquid propane volume when full the weight of the propane is specified on the tank.
Com- pare this to the tank volume take some measurements, and approx- imate the tank shape as a cylinder with a hemisphere on each end. Explain the discrepancy. As in the U. Convert 32 psig to these units. Is this equation dimensionally cor- rect? If not, find the units of the 2. Write the equivalent equa- tion in SI units. What are the dimensions of constant C for a dimensionally consistent equation?
When filled with water at 90 F, the mass of the container and its contents is 2: Find the weight of water in the container, and its volume in cubic feet, using data from Appendix A. What are the units of specific speed? A particular pump has a spe- cific speed of Analysis of Experimental Error 1. Estimate the experimental uncertainty in the air density calculated for standard conditions Note that Determine the density and specific gravity of the American golf ball. Estimate the uncertainties in the calculated values.
The label lists the mass of the contents as g. The scales used can be read to the nearest 0: Estimate the precision with which the flow rate can be cal- culated for time intervals of a 10 s and b 1 min.
Assume that mass is measured using a balance with a least count of 1 g and a maximum capacity of 1 kg, and that the timer has a least count of 0. Estimate the time intervals and uncertainties in measured mass flow rate that would result from using , , and mL beakers.
Would there be any advantage in using the largest beaker? Assume the tare mass of the empty mL beaker is g. Determine the density and specific gravity of the British golf ball. Estimate the uncertainties in the cal- culated values. The measurements are made using a ft-diameter skid pad.
Estimate the experi- mental uncertainty in a reported lateral acceleration of 0: How would you improve the experimental procedure to reduce the uncertainty? Everyone has heard of the relatively high-tech area of fluid mechanics called streamlining of cars, aircraft, racing bikes, and racing swimsuits, to mention a few , but there are many others. All of these developments depend on understanding the basic ideas behind what a fluid is and how it behaves, as discussed in this chapter.
The platter also spins at something greater than revolutions per second! The friction is due to both the effect of air viscosity on the spinning disk and oil viscosity in the bearings. Designing such a bearing presents quite a challenge.
Until a few years ago, most hard drives used ball bearings BBs , which are essentially just like those in the wheel of a bicycle; they work on the principle that a spindle can rotate if it is held by a ring of small spheres that are supported in a cage. Hard-drive makers are increasingly moving to fluid dynamic bearings FDBs. These are mechanically much simpler than BBs; they consist basically of the spindle directly mounted in the bearing opening, with only a specially formulated viscous lubri- cant such as ester oil in the gap of only a few microns.
These bearings are extremely durable they can often survive a shock of g! FDBs have been used before, in devices such as gyroscopes, but making them at such a small scale is new. Some FDBs even use pressurized air as the lubrication fluid, but one of the problems with these is that they sometimes stop working when you take them on an air- plane flight—the cabin pressure is insufficient to maintain the pressure the bearing needs!
In Chapter 1 we discussed in general terms what fluid mechanics is about, and described some of the approaches we will use in analyzing fluid mechanics problems.
In this chapter we will be more specific in defining some important properties of fluids and ways in which flows can be described and characterized. Unless we use specialized equipment, we are not aware of the underlying molecular nature of fluids. This molecular structure is one in which the mass is not continuously distributed in space, but is concentrated in molecules that are separated by relatively large regions of empty space. The sketch in Fig. Note that the size of the gas molecules is greatly exaggerated they would be almost invisible even at this scale and that we have placed velocity vectors only on a small sample.
We wish to ask: In other words, under what circumstances can a fluid be treated as a continuum, for which, by definition, properties vary smoothly from point to point? This is an important question because the con- cept of a continuum is the basis of classical fluid mechanics.
Consider how we determine the density at a point. Density is defined as mass per unit volume; in Fig. For example, if the gas in Fig. In recent times the price and capacity of flash memory have improved so much that many music players are switching to this technology from HDDs. Eventually, notebook and desktop PCs will also switch to flash memory, but at least for the next few years HDDs will be the primary storage medium.
Your PC will still have vital fluid-mechanical components! The concept of a continuum is the basis of classical fluid mechanics. The continuum assumption is valid in treating the behavior of fluids under normal conditions. It only breaks down when the mean free path of the molecules2 becomes the same order of magnitude as the smallest significant characteristic dimension of the problem. This occurs in such specialized problems as rarefied gas flow e. For these specialized cases not covered in this text we must abandon the concept of a continuum in favor of the microscopic and statistical points of view.
As a consequence of the continuum assumption, each fluid property is assumed to have a definite value at every point in space. Thus fluid properties such as density, temperature, velocity, and so on are considered to be continuous functions of position and time. Appendix A contains specific gravity data for selected engineering materials.
The specific gravity of liquids is a function of temperature; for most liquids specific gravity decreases with increasing temperature.
Other fluid properties also may be described by fields. A very important property defined by a field is the velocity field, given by V! You just clipped your first slide!
Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips. Visibility Others can see my Clipboard. PDF Excerpt: Selected type: Added to Your Shopping Cart. Evaluation Copy Request an Evaluation Copy. Mitchell ISBN: Student View Student Companion Site.
About the Author Philip J. A new case study begins each chapter, providing students with motivation and demonstrating how fluid mechanics concepts are applied to solve real-world problems.
Restructured and Updated Chapters: Including chapters related to Internal Incompressible Viscous Flow, Flow Measurement, Compressible Flow Chapters 12 and 13 of the previous edition have been combined into one comprehensive chapter on Compressible Fluids. What's New This text is well regarded as an undergraduate textbook for its comprehensive treatment of all the main areas of fluid mechanics, as well as its level of presentation.