…To our Family
Depy
Andreas
Nikos
Giannis
Lilian
…as without their support none of this would have ever been possible for us
Engineering, Energy and Architecture Set
coordinated by
Lazaros E. Mavromatidis
Volume 2
First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd
27-37 St George’s Road
London SW19 4EU
UK
www.iste.co.uk
John Wiley & Sons, Inc.
111 River Street
Hoboken, NJ 07030
USA
www.wiley.com
© ISTE Ltd 2018
The rights of Christina G. Georgantopoulou and George A. Georgantopoulos to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.
Library of Congress Control Number: 2018932715
British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-78630-139-0
This book presents an extended and detailed analysis of both the flow phenomena in closed and open channels and the flows around solid bodies. It comprises two volumes. This book is a specialized resource for those students, engineers and researchers who want to focus on the industrial applications of flows and study the fascinating world of internal and external flow phenomena.
We have both had extensive experience in teaching, studying and researching fluids since the completion of our respective PhD theses. We felt that it was time to write about the practical and analytical aspects of flow applications, all of which can be applied in industrial flows, to support researchers, engineering students and industrial engineers in the field of fluids in order to optimize their work in “flows”.
For the first author, the “fluids direction” began in the early stages of her PhD thesis study in Computational Fluid Dynamics in 1998 at the National Technical University of Athens. The second author’s knowledge of the fluids’ path is very extensive, obtained from more than 45 years of studies and work involved in his PhD thesis and further research work at the University of Patras, as well as through his position as Professor of Aerodynamics at the Hellenic Air Force Academy, spanning more than 35 years.
We have both gained substantial experience in Fluid Mechanics research through numerous publications, presentations at international conferences, academic textbook authoring, teaching through international experiences and collaborations. However, we felt that more should be offered to the Fluid Mechanics community, and hence this book.
Although we both have experience in writing for academic textbooks, this is our first publication that caters to international students, researchers and engineers, considering the industrial phenomena that are met in international industries and we have tried to present most of the applications in flows inside or around bodies. This book is based on books written previously by us on Fluid Mechanics and on Aerodynamics, but for the first time our work focuses on the practical aspects of industrial internal and external flows.
Christina, the first author, offers this textbook to the Bahrain polytechnic engineering students and all the industrial delegates who have worked with her in “flows” for many years. She also wishes to express her appreciation for her colleagues, namely Payal Modi, for the thousands of hours of constructive discussions and collaborations in fluids aspects, to Lazaros E. Mavromatidis for his support during the publishing procedure, to her father George who has been her mentor for all these years and to Stephanie Sutton and Amerissa Kapela for their continuing support with the quality of the academic English language. Additionally, George, the second author, wishes to share his more than 40 years of experience in fluids with the fluids community around the world and support them in their “flows” work as best he can.
We both have a special sentimental feeling for this book in that we are extremely proud that we have been able to write, publish and offer it to you, hoping that it will really support you in your fluids journey. We have both worked on fluids with a passion not only for our students, but also to honor our colleagues around the world. We are equally happy to say that the Fluid Mechanics community has been served by the same family for more than 40 years. We hope that we will be physically and mentally healthy to continue to serve our students and support our colleagues in the fluids aspects in the future.
We hope that you will enjoy this book and be engaged with the fascinating world of flows.
Christina G. GEORGANTOPOULOU
George A. GEORGANTOPOULOS
February 2018
Fluid Mechanics consist of two main categories. The first one refers to the quantitative and qualitative analysis and study of fluids in motion, the velocity or acceleration as well as the forces exerted by nature. The second category analyzes the physical forces that are developed on solid–fluid interfaces, where the solids represent the containers. The first category can be called Theoretical Fluid Mechanics, while the second one is called Applied Fluid Mechanics.
This book primarily presents the aspects and problems of internal and external flows, including certain fundamental principles of fluids.
To develop an extended study of Applied Fluid Mechanics problems, mathematical modeling and analysis is considered necessary. On the other hand, the empirical or experimental investigation of fluid phenomena only provides us with certain measurements and information about individual cases, and it is often difficult to generalize our conclusions. Hence, the appropriate way to study fluid flows is to investigate the related phenomena with a combined analytical–computational and experimental approach in order to improve step by step the proposed fluid theories or solutions.
Industrial engineers have raised various issues related to the main assumption that all fluids are considered to be ideal. In order to overcome these issues, every technological problem is considered to be an individual one, resulting in a lack of theoretical background. Year after year, a huge gap has been created between theoretical and practical hydrodynamics researchers, which exists even today. This book bridges this gap between various industrial flows, and an attempt has been made to present a common strategy. The flows inside pipes or channels as well as the flows around bodies are considered to be real life applications, setting the appropriate theoretical background simultaneously.
The Fluid Mechanics study comprises fluid motion and fluid balance. During the last decades, it has evolved in two major directions. Theoretical Fluid Mechanics includes the mathematical exploitation of fluid phenomena, and Technical Fluid Mechanics includes the applications of mechanical engineering, aeronautics, shipbuilding and meteorology. Technical Fluid Mechanics is considered an applied science, and hence it is often referred to as Applied Fluid Mechanics, which includes the possible solutions of fluid problems and the explanation of natural phenomena. Moreover, it aims to produce numerical predictions or experimental validation for direct practical applications.
Classic Fluid Mechanics can be derived from various areas according to the mechanical condition or fluid properties. The categories presented in Table I.1 are based on the motion of fluids as well as on compressibility, where the density varies according to the fluid condition.
Table I.1. Fluid Mechanics categories
| Fluid mechanics | Fluids at rest | Fluids in motion |
| Hydrodynamics (ρ=ct) | Hydrostatics | Hydrodynamics |
| Aeromechanics (ρ≠ct) | Aerostatics | Aerodynamics |
Units are fundamental for physics, especially for all the applied sciences such as mechanical engineering. The number without units means absolutely nothing for Fluid Mechanics, as it represents a natural quantity such as pressure, velocity or force.
Historically, various systems of units have been developed according to the theoretical principle demands or to practical applications. In most countries (not including the USA), the metric system is the official system of measurement, which is accepted by both scientists and engineers. The International System of Units (SI) was defined and established at the 11th General Conference on Weights and Measures, where more than 36 countries accepted it to be the most complete and appropriate one, including the USA. Since then, the USA has made huge progress in introducing SI units to engineering. For example, many NASA laboratories use SI units for their technical research results, and the AIAA (American Institute of Aeronautics and Astronautics) also supports the SI in its research papers.
Therefore, students who want to study engineering have to know both unit systems. The following table presents the corresponding basic units in both systems based on the theory that all the derived units at the metric system can be produced by the base ones.
Table I.2. Base units in SI and BS (British system)
| Base quantity | SI | BS |
| Length | Meter (m) | Foot (ft) |
| Time | Second (s) | Second (sec) |
| Mass | Kilogram (kg) | Pounds of mass (lbm) or slug |
| Temperature | Celsius (°C) | Fahrenheit (°F) |
| Absolute temperature | Kelvin (K) | Rankine (R) |
As we have just mentioned, the derived units can be produced by the base units following the nature of interrelationships or the basic formulas with the need for adding any conversion factor, as in the following, using Newton’s law:
Thus, we further confirm the definition of Newton as the force that is required to accelerate a mass of 1 kg at a rate of 1 m/s2. Similarly, the ideal gas constant for air (R=287 J/(kg·K) can also be expressed in the following way:
The BS is also a consistent system, and the same procedure can be followed for the derived quantities:
However, more systems of units are not consistent; therefore, it is necessary to use a factor in order to produce the required conversion as shown below. These systems have been used in the past by engineers but have often not been convenient to be applied:
The various temperature units are of high importance. We often denote absolute temperature by T, where the minimum temperature value can be zero. Kelvin (K) and Rankine (R) are the absolute temperature units, where 0 R = 0 K indicates the temperature at which all the molecular motion theoretically stop. In addition, the relationships among the temperature units are:
It is worth mentioning that the temperature T in the ideal gas equation of state (equation [I.9]) is absolute:
where ρ is the pressure, ρ is the density of gas and the other symbols are defined as above.
Table I.3. Units of common quantities in physics and fluids
| Natural quantity | Units | Symbol |
| Force | Newton | N = kg m/s2 |
| Energy | Joule | J = N m |
| Power | Watt | W = J/s |
Table I.4. Common metric prefix in SI
| 10−6 | micro | μ |
| 10−3 | milli | m |
| 103 | kilo | k |
| 106 | mega | M |
Table I.5. Length, area and volume conversion factors
| Length l | |
| 1 in | 25.4 mm |
| 1 ft | 0.3048 m |
| 1 yd | 0.9144 m |
| 1 mile | 1.6093 km |
| Area S | |
| 1 in2 | 645.16 mm2 |
| 1 fr2 | 0.0929 m2 |
| 1 yd2 | 0.8361 m2 |
| 1 mile2 | 2.590 km2 |
| 1 acre | 4046.9 m2 |
| Volume v | |
| 1 in3 | 16387 mm3 |
| 1 ft3 | 0.02832 m3 |
| 1 UK gal | 0.004546 m3 |
| 1 US gal | 0.003785 m3 |
Table I.6. Conversion factor mass, density, force, viscosity and pressure
| Mass m | |
| 1 kg | 103 g |
| 1 oz | 28.352 g |
| 1 lb | 453.592 g |
| 1 cwt | 50.802 kg |
| 1 ton (UK) | 1016.06 kg |
| Density ρ | |
| 1 lb/ft3 | 16.019 kg/m3 |
| 1 lb/UK gal | 99.776 kg/m3 |
| 1 lb/US gal | 119.83 kg/m3 |
| Force F | |
| 1 dyne | 10−5 N |
| 1 poundal | 0.1383 N |
| 1 lb-f | 4.4482 N |
| 1 kg-f | 9.8067 N |
| 1 ton-f | 9.9640 kN |
| Viscosity μ | |
| 1 poise (1 g/cm sec, 1 dyn sec cm2) | 0.1 N sec/m2 |
| 1 lb/ft sec (1 poundal sec/ft2) | 1.4882 N sec/m2 |
| 1 lb/ft hr (1 poundal hr/ft2) | 0.4134 mN sec m2 |
| Pressure p | |
| 1 bar (105 dynes/cm2) | 105 N/m2 |
| 1 atm (1 kg-f/cm2) | 98.0665 kN/m2 |
| 1 atm (standard) | 101.325 kN/m2 |
| 1 psi (1 lb-f/in2) | 6.8948 kN/m2 |
| 1 psf (1 lb-f/fn2) | 47.880 N/m2 |
Table I.7. Other conversion factors
| Energy E | ||
| 1 erg | 10−7 J | |
| 1 ft poundal | 0.04214 J | |
| 1 ft lb-f | 1.3558 J | |
| 1 cal (international table) | 4.1868 J | |
| 1 Btu | 1055.06 J | |
| 1 hph | 2.6845 MJ | |
| 1 kwh | 3.6 MJ | |
| Power P | td | |
| 1 erg/sec | 10−7 W | |
| 1 hp (British) | 745.70 W | |
| 1 hp (metric) | 735.40 W | |
| 1 ft lb-f/sec | 1.3558 W | |
| 1 Btu/hr | 0.2931 W | |
| Surface tension σ | ||
| 1 dyne/cm (1 erg/cm2) | 10−3 J/m2 | |
| Moment of inertia M | ||
| 1 lb.ft2 | 0.04214 kg m2 | |
| Momentum J | ||
| 1 lb-fit/sec | 0.1383 kg.m/sec | |
| Specific temperature c | ||
| 1 Btu/lb°F (1 cal/g.°C) | 4.1868 kJ/kg.°C | |
| Heat transfer coefficient h | ||
| 1 Btu/h.ft2.°F | 5.6783 W/m2.K | |
| Thermal conductivity K | ||
| 1 Btu/h.ft.°F | 1.7307 W/m.K | |
| Water (18°C and air properties (STP)) | ||
| Water | Air | |
| Density (kg/m3) | 103 | 1.3 |
| Viscosity (N sec/m2) | 10–3 | 1.7 × 10–5 |
| Specific heat (KJ/kg.K) | 4 | 1 |
| Thermal Conductivity (W/m.K) | 0.6 | 0.024 |