Fluctuations in the number of particles (or droplets and bubbles) are observed in experiments of multiphase flows, and these also manifest as fluctuations of the dispersed–phase volume fraction. The intensity of these fluctuations is characterized using a mathematical description based on second–order statistics. The intensity and range of fluctuations in the clustering regime of a granular gas...

Gaseous fluids may move slowly, as smoke does, or at high speed, such as occurs with explosions. High-speed gas flow is always accompanied by low-speed gas flow, which produces rich visual details in the fluid motion. Realistic visualization involves a complex dynamic flow field with both low and high speed fluid behavior. In computer graphics, algorithms to simulate gaseous fluids address eith...

Dust emissions can have significant effects on the human health, environment and industry equipment. Understanding the dust generation process helps to select a suitable dust preventing approach and also is useful to evaluate the environmental impact of dust emission. To describe these processes, numerical methods such as Computational Fluid Dynamics (CFD) are widely used, however nowadays part...

Flow measurement techniques determine velocity vector fields in liquid or gas flows. In fluid mechanics, many methods are based on seeding particles to visualize the flow imaged by an adequate camera system. The tomo-PIV (tomographic particle image velocimetry) technique presented in this paper generates time-resolved volumetric reconstructions of a particle constellation from a limited number ...

Long time (~1day) aging or reactions of aerosol is typically studied using either large aerosol chambers (>10 m 3 ) or particles supported on a substrate to minimize wall effects. To avoid wall effects in the latter, it is often essential that the wall reactivity be extremely small (<<10 -5 reactions per encounter) and that the particle loadings be very small (<1 pg/cm 2 ) to eliminate transpor...

We investigate stationary gas flows in a fixed, rotating barred potential. The gas is assumed to be isothermal with an effective sound speed cs, and the equations of motion are solved with smoothed particle hydrodynamics (SPH). Since the thermal energy in cloud random motions is negligible compared to the orbital kinetic energy, no dependence of the flow on cs is expected. However, this is not ...

The present study investigated the effect of operating parameters of a laboratory spray dryer on powder characteristics, in order to optimise the production of trehalose and raffinose powders, intended to be used as carriers of biomolecules for inhalation. The sugars were spray dried from 80:20 methanol:n-butyl acetate (v/v) solutions using a Büchi Mini Spray dryer B-290. A 2(4) factorial desig...

The circumnuclear disk and ionized gas filaments as remnants of tidally disrupted clouds Abstract. Sticky particle calculations indicate that a coherent structure , a dispersion ring, forms when a cloud on a low angular momentum orbit passes close to the dynamical center of a potential containing a point mass. The cloud is tidally stretched and differentially wrapped, and dissipation in shocks ...

The size specifications for suitable tracer particles for particle image velocimetry (PIV), particularly with respect to their flow tracking capability, are discussed and quantified for several examples. A review of a wide variety of tracer materials used in recent PIV experiments in liquids and gases indicates that appropriately sized particles have normally been used. With emphasis on gas flo...

Liquid flow from a column is nebulised using nitrogen or air to give a plume of fine droplets containing the analyte in solution. The liquid droplets pass into a heated zone where the solvent is removed to leave the dried analyte particle which is subsequently irradiated with light. The amount of light scattered is then measured. Gas flow and temperature can be adjusted to optimise the response...