In two earlier papers, (1'2) referred to here as I and II, respectively, we showed how to calculate the drag force on a macroscopic sphere or cylinder moving through a dilute gas by using an extended Boltzmann equation. This equation differs from the usual Boltzmann equation in that it treats the effect of collisions between.gas molecules and the macroscopic object as a term in the Boltzmann eq...

The purpose of this investigation was to validate a new system of breath-bybreath expired gas analysis to both an artificial working model of lung ventilation and gas exchange as well as to the Douglas bag technique. In addition, comparisons will be made between expired fractions, ventilation, and computations of VO2, VCO2, and RER between the new system and a commercial mixing chamber system (...

There are two distinctive methods in describing the motion of fluid flows mathematically. One is based on the conservation laws of mass, momentum, and energy, and the associated constitutive relations representing the inherent properties of fluid media, which is called the Navier-Stokes-Fourier (NSF) equations in the literature. Another is based on the stochastic partial differential equation o...

This paper presents the initial stage of an effort aimed at developing a new correlation to estimate pseudo critical properties for sour gas when the exact composition is not known. Several mixing rules and gas gravity correlations available in the literature are first evaluated and compared. The evaluation is performed on a large database consisting of more than 2106 samples of sour gas compos...

The study of the comet coma, or its tenuous atmosphere, is a major space application of rarefied gas dynamics, which requires modeling the gas flow in a wide range of Knudsen number. For weak to moderate comets, only the subsolar region of the coma is in a collision dominated regime. In the low density regions of the upper atmospheres of the planets and the planetary satellites and the middle t...

A Monte Carlo technique is described for simulating the high-speed flow of a rarefied gas around a cylindrical body. The method uses a hard-sphere model, or, alternatively, the "Maxwellian" model to compute collisions between particles. A representative "test particle" is scattered in such a way that its statistical behavior approximates that of a random particle chosen from the actual gas. Thi...

The effect of short pulsing mixing interruptions on the Aspergillus niger R3 morphology and fermentation performance was studied in 5 l agitated fermenters with double Rushton turbine impellers. A stable increase in the mycelia concentration and higher biomass concentrations at the end of the process were achieved in two continuous mixing fermentations, while in two fermentations with mixing in...

The purpose of this paper is to illustrate that direct simulation Monte Carlo methods can often be considered as rigorous mathematical tools for solving nonlinear kinetic equations numerically. First a convergence result for Bird’s DSMC method is recalled. Then some sketch of the history of stochastic models related to rarefied gas dynamics is given. The model introduced by Leontovich in 1935 p...

Viscous resistance to changes in the volume of a gas arises when different degrees of freedom have different relaxation times. Collisions tend to oppose the resulting departures from equilibrium and, in so doing, generate entropy. Even for a classical gas of hard spheres, when the mean free paths or mean flight times of constituent particles are long, we find a nonvanishing bulk viscosity. Here...

The purpose of this work is to analyze the distribution bulk materials according characteristic parameters mixing process at second stage processing in a rotary apparatus. design device has wide range, including for needs agriculture, example, when forming mixtures mineral fertilizers and multifunctional pyrethroid drugs. At stage, impact interaction with bump surface rarefied flows components ...