Accession Number : ADA131538

Title :   Higher Order Numerical Simulations of the Knudsen Layer.

Descriptive Note : Interim rept. 1 Oct 81-30 Sep 82,


Personal Author(s) : Baker,R L ; Nelson,D A ; Turner,J S

PDF Url : ADA131538

Report Date : 29 Apr 1983

Pagination or Media Count : 61

Abstract : The infinitesimal nonequilibrium region (Knudsen layer) that occurs at phase interfaces when there is net mass transfer, has been theoretically investigated for the case of strong evaporation. The rate of collisional relaxation processes in the layer, which determines the net transfer of mass, momentum, and energy across the layer, has been studied using models at three levels of mathematical complexity (completeness). Calculated results obtained by Monte Carlo direct simulation of the Boltzmann equation and, by the method of Molecular Dynamics, have been compared with approximate solutions based upon the nonlinear mass, momentum, and energy conservation equations. The comparisons indicate the validity of the approximate method in predicting the essential features of the Knudsen layer region, , i.e., the net mass transfer rate and the static pressure jump across the layer, for both single and multiple species cases. We are interested in the multispecies case for the interpretation of laser-vaporized carbon ablation data to obtain vapor pressure and vaporization kinetics information. Further use of the higher order solution methods is anticipated to investigate theoretically difficult physical/chemical problems such as the effect of thermal fluctuations in nonlinear chemically reacting systems. (Author)

Descriptors :   *Evaporation, *Vaporization, *Reaction kinetics, *Phase transformations, Mass transfer, Interfaces, Layers, Vapor pressure, Carbon, Thermodynamics, Energy transfer, Boltzmann equation, Phase studies, Momentum transfer, Monte Carlo method, Nonlinear analysis, Discrete distribution, Particle collisions, Energy conservation, Mathematical prediction, Computerized simulation, Static pressure, Knudsen number, Laser beams, Ablation

Subject Categories : Physical Chemistry
      Numerical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE