The Boltzmann equation for inelastic and rough hard spheres is considered as a model of a dilute granular gas. In this model, the collisions are characterized by constant coefficients of normal and tangential restitution, and hence the translational and rotational degrees of freedom are coupled. A normal solution to the Boltzmann equation is obtained by means of the Chapman-Enskog method for st...

We have performed three-dimensional numerical simulations of accretion discs in a close binary system using the Smoothed Particle Hydrodynamics (SPH) method. Our results show that, contrary to previous claims, 3D discs do exist even when the specific heat ratio of the gas is as large as γ = 1.2. Although the disc is clearly more spread in the z-direction in this case than it is for the quasi-is...

Isothermal gas flows in microchannels is studied using the lattice Boltzmann method. A novel equation relating Knudsen number with relaxation time is derived. The slipvelocity on the solid boundaries is reasonably realized by combining the bounce-back reflection with specular reflection in a certain proportion. Predicted characteristics in a two-dimensional microchannel flow, including slip-vel...

I consider a sample of eight pressure-supported low-surface brightness galaxies in terms Milgrom's modified Newtonian dynamics (MOND). These objects include seven nearby dwarf spheroidal -- Sextans, Carina, Leo II, Sculptor, Draco, I, Fornax, and the ultra-diffuse galaxy DF44. The are modelled as Milgromian isotropic isothermal spheres characterised by two parameters that constrained observatio...

We compute 3D models of supersonic, sub-Alfv enic, and super-Alfv enic decaying turbulence, with initial rms Alfv en and Mach numbers ranging up to ve, and an isothermal equation of state appropriate for star-forming interstellar clouds of molecular gas. We nd that in 3D the kinetic energy decays as t ? , with 0:85 < < 1:2. In 1D magnetized turbulence actually decays faster than unmagnetized tu...

Aims. We determine the central mass distribution of galaxy cluster RX J1347−1145 using strong gravitational lensing. Methods. High resolution HST/ACS images of the galaxy cluster RX J1347−1145 have enabled us to identify several new multiple image candidates in the cluster, including a 5 image system with a central image. The multiple images allow us to construct an accurate 2-dimensional mass ...

Based on driving force for crystallization of one-component gas hydrate, in this report an expression for the supersaturation for crystallization of multicomponent gas hydrate is derived. Expressions for the supersaturation are obtained in isothermal and isobaric regimes. The results obtained are applied to the crystallization of hydrates of mixtures of methane plus ethane and can apply to ...

where E(x, y) > 0. The parametric curves x = const. and y = const. form an isothermal net on 1. It is well known that h(x, y) = c, where h is a harmonic function of (x, y), that is, h satisfies the Laplace equation, hA, + h,, = 0, defines an isothermal family of curves on Z. The constant c is called the isothermal parameter. The converse of the preceding statement is not valid. That is, if g(x,...