Book contents
- Frontmatter
- Contents
- List of contributors
- Foreword
- Part one GENERAL
- Part two THEORY
- 4 Transport Properties of Dilute Gases and Gaseous Mixtures
- 5 Dense Fluids
- 6 The Critical Enhancements
- Part three DATA REPRESENTATION
- Part four APPLICATION OF SELECTED METHODS
- Part five APPLICATION TO SELECTED SUBSTANCES
- Part six DATA BANKS AND PREDICTION PACKAGES
- Index
4 - Transport Properties of Dilute Gases and Gaseous Mixtures
Published online by Cambridge University Press: 07 October 2009
- Frontmatter
- Contents
- List of contributors
- Foreword
- Part one GENERAL
- Part two THEORY
- 4 Transport Properties of Dilute Gases and Gaseous Mixtures
- 5 Dense Fluids
- 6 The Critical Enhancements
- Part three DATA REPRESENTATION
- Part four APPLICATION OF SELECTED METHODS
- Part five APPLICATION TO SELECTED SUBSTANCES
- Part six DATA BANKS AND PREDICTION PACKAGES
- Index
Summary
Introduction
Transport coefficients describe the process of relaxation to equilibrium from a state perturbed by application of temperature, pressure, density, velocity or composition gradients. The theoretical description of these phenomena constitutes that part of nonequilibrium statistical mechanics that is known as the kinetic theory. The ultimate purpose of this theory is to relate the macroscopic (observable) properties of a system to the microscopic properties of the individual molecules and their interaction potentials.
The kinetic theory of dilute gases assumes a macroscopic system at densities low enough so that molecules most of the time move freely and interact through binary encounters only. Nevertheless, the densities are high enough to ensure that the effects of molecule–wall collisions can be neglected compared to those from molecule–molecule encounters. The first condition implies that the thermodynamic state of the fluid should be adequately described by a virial expansion up to and including the second virial coefficient. The second condition means that the mean free path of molecules is much smaller than any dimension of the vessel and that Knudsen effects play no significant role.
It is worth noting that in this context the terms ‘dilute’ or ‘low–density gas’ represent a real physical situation, whereas the frequently used expression ‘zero–density limit’ is related to results of a mathematical extrapolation of a density series of a particular transport property at constant temperature to zero density.
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- Chapter
- Information
- Transport Properties of FluidsTheir Correlation, Prediction and Estimation, pp. 29 - 65Publisher: Cambridge University PressPrint publication year: 1996
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