Accession Number : AD0671123

Title :   LINEARIZED RAYLEIGH PROBLEM WITH INCOMPLETE SURFACE ACCOMMODATION,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Epstein,Melvin

Report Date : MAR 1968

Pagination or Media Count : 43

Abstract : A kinetic theory treatment of the linearized Rayleigh problem was performed with the BGK model of the Boltzmann collision integral and various models of the wall boundary condition. The models allow consideration of the dependence of the character of the gas surface interaction on the velocities of the incident particles. Two classes of these models are considered. In the first, the particles reflected nonspecularly are assumed to have an isotropic velocity distribution; in the second class, the nonspecularly reflected particles are assumed to have an anisotropic velocity distribution. Analytical asymptotic solutions are obtained for the short-time (near-free-molecule flow) and long-time (near-continuum flow) behavior. The results indicate that incomplete accommodation considerably lengthens the time required for continuum flow to be established. The method of matched asymptotic expansions is used to obtain long-time solutions, which are uniformly valid in the Knudsen layer and far from the wall. It is found that the slip coefficient, which is evaluated from these solutions as a function of the parameters associated with the gas-surface interaction, may be significantly greater than the value predicted by the Maxwell model when the degree of accommodation is small. (Author)

Descriptors :   (*HEAT TRANSFER, AERODYNAMIC CHARACTERISTICS), SURFACES, GASES, LINEAR SYSTEMS, EQUATIONS OF MOTION, KINETIC THEORY, INTERACTIONS, BOUNDARY LAYER, PARTICLES, RAREFIED GAS DYNAMICS

Subject Categories : Aerodynamics
      Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE