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...

Based on the Boltzmann-BGK (Bhatnagar-Gross-Krook) equation, in this paper a discrete unified gas kinetic scheme (DUGKS) is developed for low-speed isothermal flows. The DUGKS is a finite-volume scheme with the discretization of particle velocity space. After the introduction of two auxiliary distribution functions with the inclusion of collision effect, the DUGKS becomes a fully explicit schem...

The non-kinetic models typically offer a more straightforward approach than the complex kinetic for microchannel gas flow problems. However, their applicability has traditionally been limited to certain range of rarefaction. Hence, various modifications, including slip boundary condition, non-linear viscosity, and diffusion phenomena, have proposed. Although less explored, wall-to-wall collisio...

We examine highly super-Eddington black-hole models for SS 433, based on two-dimensional hydrodynamical calculations coupled with radiation transport. The super-Eddington accretion flow with a small viscosity parameter, α = 10, results in a geometrically and optically thick disk with a large opening angle of ∼ 60 to the equatorial plane and a very rarefied, hot, and optically thin high-velocity...

The classical BGK model for describing the flow of a rarefied gas in a cylindrical tube is used as a starting point for developing an equivalent integral-equation formulation of the considered class of problems. While the problems of Poiseuille flow and thermal creep in a cylindrical tube have already been well solved in terms of a pseudo problem obtained from an integral-equation definition of...

A unidirectional flow of a rarefied gas between two parallel plates driven by a uniform external force is investigated on the basis of kinetic theory with special interest in the behavior in the near continuum regime. The Bhatnagar-Gross-Krook (BGK) model of the Boltzmann equation and the diffuse reflection boundary condition are employed as the basic system. First, a systematic asymptotic anal...