Vacuum physics is the necessary condition for scientific research and modern high technology. In this introduction to the physics and technology of vacuum the basic concepts of a gas composed of atoms and molecules are presented. These gas particles are contained in a partially empty volume forming the vacuum. The fundamentals of vacuum, molecular density, pressure, velocity distribution, mean ...

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...

To show the effects of the particles and forced disturbances on the instantaneous large-scale vortex structures in a gas-particle round jet, coherent structures in gas-particle turbulent round jets were investigated experimentally by flow visualization. The 45m and 350m diameter glass beads were used as the particles in the experiments. An acoustic speaker was used to introduce velocity perturb...

Nanoparticles of nickel have been prepared by laser-driven decomposition of nickel carbonyl. In this method, an infrared laser rapidly heats a dilute mixture of nickel carbonyl and a photosensitizer in a carrier gas to decompose the precursor and initiate particle nucleation. To produce nickel nanoparticles, nickel carbonyl was generated in situ from activated nickel powder and CO at room tempe...

A Lagrangian-Eulerian methodology is developed for the numerical simulation of a gas-solid reactive flow. The SO2-NOx Adsorption Process (SNAP) is taken as a test case. A three-dimensional time dependent simulation is performed. A notional particle based Monte-Carlo algorithm is used to solve the transported composition Probability Density Function (PDF) equations to determine the gas phase com...

To monitor the gas and solid streams in a downcomer of a J-valve in a CFB, the simultaneous measurement technique using the oxygen gas tracer, the hot particle tracer and the pressure drop was developed. By using this novel measurement technique, the dependence of the solid flow on the gas flow in the moving bed in the downcomer of J-valve was investigated. The pressure profile and the pressure...

In the present study, we develop a new numerical procedure to simulate a three-phase (i.e. solidgas-liquid) flow with a free surface. One of the typical three-phase flows can be seen at the impact phenomenon of a solid particle to a free liquid surface. In the case, the particle rapidly decelerate at the impact position, and then sink into the liquid. In addition, at the impact, air bubbles are...

as a native fermented dairy drink, doogh is an important industrial product in iran. however, its characteristics have not been completely evaluated. this study evaluated the flow behavior, particle size distribution and stability of non-fat doogh as affected by the row material employed (fresh skim milk or skim milk powder) and the total solids (ts) content of the final drink. the viscosity of...

Abstract The effect of the solid–wall boundary condition on the segregation behavior of a sand ternary mixture differing in size but having the same proportion has been investigated in a gas–solid bubbling fluidized bed. A multi-fluid computational fluid dynamics model incorporating the kinetic theory of granular flow has been used. The mass fraction profiles of the different-sized partic...