摘要:

The passage of a weak vorticity disturbance through a reactive shock wave, or detonation, is examined by means of a linearized treatment. Of special interest is the effect of chemical heat release on the amplification of vorticity, in particular, and on the disturbance pattern generated downstream of the detonation, in general. It is found that the effect of exothermicity is to amplify the refracted waves. The manner in which the imposed disturbance alters the structure of the detonation itself is also discussed.

ISSN:0899-8213    

DOI:10.1063/1.857626

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A kinetic theory for a mixture of &ngr;‐polyatomic gases of perfectly rough, perfectly elastic, and rigid spherical molecules is developed. A macroscopic state of the mixture is characterized by 16&ngr;+1 fields of partial densities, partial velocities, partial pressure tensors, partial translational heat fluxes, partial rotational heat fluxes, and temperature of the mixture. The generalized laws of Fick, Fourier, and Navier–Stokes are obtained from an iteration method akin to the Maxwellian procedure. As an application, the transport coefficients for binary mixtures of CH4–CF4, CH4–CD4, and CD4–CF4are determined.

ISSN:0899-8213    

DOI:10.1063/1.857819

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The forces on droplets in Poiseuille flow in the Reynolds number range from 0.7 to 27 are determined experimentally. It is found that droplets migrate toward the centerline and experience drag considerably in excess of that prevailing in uniform flow. Rough correlations for the drag and lift coefficients as functions of the Reynolds number and a parameter characterizing the flow nonuniformity are developed.

ISSN:0899-8213    

DOI:10.1063/1.857627

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The periodic laminar flow of an incompressible fluid existing within a rectangular chamber when one of the walls is oscillated sinusoidally, and, where fluid can enter and leave the chamber through a small orifice in the stationary wall opposite to the oscillating surface, is examined numerically using a newly developed iterative algorithm (SIMPLE‐TP) valid for incompressible and time‐periodic flows. Results indicate the presence of a high‐velocity jet emanating from the orifice during that portion of the oscillation cycle when the wall recedes from the orifice and also show the presence of at least one counter‐rotating vortex pair during all parts of the oscillation cycle.

ISSN:0899-8213    

DOI:10.1063/1.857628

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A sensitive test is proposed for the accuracy in the evaluation of the molecular collision number in the direct‐simulation Monte Carlo method: It is shown that the translational relaxation in a spatially homogeneous box, which is divided into a number of cells where the simulation of molecular collisions is carried out, is a simple but sensitive test problem for the evaluation of the lower limit of mean molecular number per cell, ⟨&Dgr;N⟩min, and the computation time, as well as for the verification of the accuracy in the evaluation of the collision number. It is confirmed from the test that ⟨&Dgr;N⟩minis about 1 for the null‐collision (NC) technique but about 30 for the time‐counter (TC) technique, and the computation time for the NC technique is about 10%–40% larger than that for the TC technique in the simulation with the same molecular number.

ISSN:0899-8213    

DOI:10.1063/1.857577

出版商:AIP    

年代:1990

数据来源: AIP