Accession Number : AD0291772

Title :   KINETIC METHODS AND THE FREE EXPANSION PROBLEM,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MA

Personal Author(s) : Florance, E. T.

Report Date : 15 NOV 1962

Pagination or Media Count : 34

Abstract : An investigation is made of various techniques used to treat rarefied gases by means of kinetic theory. Two formal parametric expansions, the Chapman-Enskog procedure and Knudsen iteration, are reviewed as applied to the single relaxation time (Krook) model. A brief presentation of the Grad moment method is given, and the thirteen-moment equations are discussed. The Krook model is formally solved, and the solution is compared with the result of the Chapman-Enskog procedure. An approximation method is suggested to account for the existence of a time-like boundary layer in solutions of the kinetic equation. The free expansion of a gas is considered, and two well-known exact solutions for the Euler and Knudsen limits are quoted. Interpolation formulas are constructed to connect exact solutions for both limits through the entire range of Knudsen number. The possibility of incorporating kinetic effects into the known solutions by using other methods is also discussed. (Author)

Descriptors :   *GAS FLOW, *KINETIC THEORY, *RAREFIED GAS DYNAMICS, EXHAUST GASES, GUIDED MISSILES, INTEGRAL EQUATIONS, MATHEMATICAL ANALYSIS, RELAXATION TIME, THEORY.

Distribution Statement : APPROVED FOR PUBLIC RELEASE