Properties Of Dilute Gases Research Articles

Comparison of predictions of dilute gas bulk properties on the basis of some new krypton potentials

The krypton potentials of Barker et al., Buck et al., Gough et al. (Maitland and Smith (n-6)) and Thakkar and Smith (MIST 2C and 6B) are compared as to their ability to predict dilute gas properties (second virial, viscosity, self-diffusion and thermal conductivity coefficients and thermal diffusion factors). The potentials of Barker et al. and Buck et al. and Gough et al. (MS) accurately predict these properties almost equally. The MIST potentials do not fare quite so well. The isotopic thermal diffusion factor, the dilute gas property most sensitive to the shape of the potential, is best described by the Buck et al. and MS potentials. An analysis of this property suggests the correctness of the slope of the repulsive wall of these potentials.

Collisionally Uncoupled Model for the Contribution of Orientational Polarizations to Transport Properties of Dilute Gases. I

A simple collisionally uncoupled model of the contribution of orientational polarizations to the transport properties of dilute gases is proposed. This takes detailed account of the molecular free motions between collisions, and so encompasses a variety of phenomena associated with the decoupling of angular momenta by relatively strong external fields.

Magnetic and Electric Effects on Transport Properties

with an introdu ctory section in which the recent history of the subject is presented along with a short outline of the underlying physics. A survey of the principal developments will then be given. In order to facilitate the review procedure, the subject matter will be sub divided in the following manner: the influence of a static magnetic field on the transport properties of dilute gases is split into two parts, one treat­ ing theory and the other experiment; this is followed by a section dealing with the analogous situation in a rarefied gas; then, related work concerning the influence of a static electric field on the transport properties of polar gases is described; and, finally, the influence of alternating fields on the trans­ port properties is covered briefly.

The rigid sphere perturbation procedure for theoretical evaluation of the transport coefficients of pure gases

A new approximation procedure for the evaluation of the transport properties of dilute gases. has been developed by considering the actual intermolecular potential energy function as a perturbation over the rigid-spherical one. The computed numerical results reveal that as expected the proposed procedure, though much simpler, is almost as convergent as the Chapman-Cowiing one and more so at higher temperature. A very useful by-product of the study is the information regarding the complementary character of the Kihara and the proposed procedure viz. that the Kihara procedure is suitable only for the lowest temperature while the present one is far more superior both for moderate as well as highest ones but is slighlt inferior to Kihara one only at the lowest temperatures.

Recent advances concerning the transport properties of dilute gases

Some theoretical and experimental developments of the last decade are discussed with emphasis on techniques that can be used to calculate viscosity, thermal conductivity, and diffusion coefficients assuming appropriate interatomic or intermolecular force laws. Three main topics are considered: First, intermolecular potential energy functions for which collision integrals are now available; second, heat conduction in chemically reacting gases; and finally, a closely related topic, the heat conductivity of polyatomic gases.

Time-Correlation Functions in the Statistical Mechanics of Transport Processes

A kinetic equation governing the time dependence of the correlation function of flux is established for dilute gases and is integrated to yield a relation between the correlation time and the transport cross section. The spectrum of the binary collision operator is determined for spherically symmetric forces between molecules, which, for the hard-core model, consists of two discrete values in the classical limit; hence it is shown that the question of validity of approximating the correlation function by an exponential decay depends upon the type of intermolecular force and the temperature of the system. Approximate eigenvalues of the master collision operator are obtained corresponding to the fluxes of viscosity and thermal conduction, and their relations to the macroscopic transport coefficients are derived. These relations lead to a new approach to the transport properties of dilute gases, which is different from Enskog-Chapman's method, but yields the same results in the classical limit. An expansion formula for the canonical transformation describing the motion of dilute gases is obtained and is employed to clarify the assumption of random a priori phases in the momentum representation for spatially uniform gases; this is done by formulating the quantum-mechanical equivalent of Brout's idea in the classical derivation of the master equation.