Environmental Fluid Dynamics

Flow Processes, Scaling, Equations of Motion, and Solutions to Environmental Flows

Jorg Imberger

• Publisher: Academic Press
• Year: 2012
• ISBN:
  9780080916705
• Topic: Sciences biologiques
• Subtopic: Science environnementale

Environmental Fluid Dynamics provides an introduction to the principles of environmental fluid dynamics, i.e., nature's use of air and water to transport and transform waste into nutrients for various organisms.

The author, a Professor of Environmental Engineering and the Director of the Centre for Water Research at the University of Western Australia, is careful to include the appropriate mathematical expressions for the fundamentals of fluid dynamics without overburdening the reader with difficult or extensive notation.

Starting with a discussion of the basics of fluid dynamics for undergraduates, the book moves on to more detailed material for graduate students and specialists in environmental engineering and/or science, physical limnology, estuarine dynamics, and coastal oceanography. Topics covered include equations of motion, fluid viscosity, environmental hydraulics, mixing and dispersion, surface waves, and environmental flows. The materials presented are based on the author's 40 years of teaching fluid dynamics at Berkeley, Caltech, Karlsruhe, Padova, and Western Australia.

The book provides a basic overview, while specialists needing more in-depth information can to turn to advanced texts in their specific areas of interest.

• Introduces the principles of fluid dynamics, follows with simple applications, and builds to more complex applications experienced in the field
• Offers a unique, authoritative, and accessible treatment of the subject
• Includes appropriate mathematical expressions without overburdening the reader with difficult or extensive notation

Chapter 1

Physical Quantities, Dimensional Analysis, Scaling and Bulk Conservation Equations

Contents

1.1. Physical Quantities

1.2. Dimensional Analysis

1.3. Fluid Properties

1.3.1. Nature of Fluids: Gases and Liquids

1.3.2. Vapor Pressure

1.3.3. The Continuum Concept

1.3.4. Mass of a Fluid

1.3.5. Pressure and Compressibility

1.3.6. Temperature

1.3.7. Specific Heat

1.3.8. Coefficient of Thermal Expansion

1.3.9. Viscosity

1.3.10. Surface Tension

1.3.11. The Equation of State of Air

1.3.12. The Equation of State of Water

1.4. Flow Domains, Scaling and Modeling

1.5. Dynamic Similarity

1.6. Hydrostatic Pressure

1.7. Pressure Forces on a Surface

1.8. Control Volumes

1.9. Introduction to the Kinematics of Flow

1.10. Bulk Conservation of Mass

1.11. Bulk Conservation of Momentum

1.12. Bulk Conservation of Energy

1.13. Solving Problems Using the Conservation Laws

In this chapter, we present an overall introduction to the remainder of this book, from the point of view of a student who has had an undergraduate education in applied science or engineering or a researcher in the chemical or biological sciences who wishes to gain an introduction to fluid dynamics. The calculus that is required to understand the material is summarized in the Appendix.

1.1 Physical Quantities

Physical quantities are entities that quantify and describe some particular physical state. Everybody is familiar with quantities such as the volume of a bottle of milk, the weight of a suitcase, the speed of a motorcar and so on. As we shall see later such physical quantities may differ widely, but all possess two main attributes, a number to describe the magnitude or size of the quantity and the unit of measure used in assessing the magnitude or size. The particular unit chosen for a particular physical quantity is not uniquely determined, but depends on a number of factors. Tradition is certainly the main determinant. In Europe, the unit to measure the distance between two places is called the kilometer (equivalent to 1000 m) whereas in the US, people use miles to describe the same physical quantity. How did this come about? To see this, consider what determines the choice of the unit. It is very convenient to match the unit to the magnitude so that the mind is confronted with manageable numbers as magnitudes. Again consider a simple example. The size of the old small format photographic negative was specified as 35 mm, whereas the medium format negative was specified as 6 cm × 6 cm. We see immediately, from this example, that the units, mm and cm, were chosen in each case to keep the magnitude 35 and 6 manageable.

On the other hand, if we speak of the width of a road we would quite naturally speak of a certain number of meters, but if we speak about the length of the road between say two cities we would again quite natur...