CASTELLANOS MATA , Antonio

We explore the role of gas viscosity in the behavior of gas-fluidized beds of fine powders by means of experimental measurements using nitrogen and neon as fluidizing gases, and theoretical considerations. The existence of a nonbubbling fluidlike regime has been recently observed in beds of fine powders fluidized with nitrogen. Our experiments...

The aim of this paper is to explore the capability of Discontinuous Galerkin Finite Element methods to solve numerically the charge transport equation in EHD convective flows, in both strong and weak injection regimes. These methods are especially suited to treat purely hyperbolic problems, as it is the charge transport equation in most EHD...

A set of one‐dimensional models, previously derived for liquid jets, is generalized to viscous liquid bridges by applying suitably modified boundary conditions at the anchoring disks. A linear analysis for small‐amplitude perturbations around the cylindrical static solution is performed. The oscillation frequencies and growth factors so...

Some years ago it was shown that gas-fluidized powders may transit from solidlike to fluidlike fluidization prior to bubbling, shedding light on a long-standing controversy on the nature of "homogeneous" fluidization. In this paper it is shown that some gas-fluidized powders may also transit from the fluidlike regime to elutriation, with full...

Fine particles agglomerate in the fluidized state due to the strength of interparticle attractive forces as compared to particle weight. Interparticle adhesion can be largely increased by consolidation stresses applied during powder handling. As a consequence, fragments of the consolidated powder may persist when the powder is fluidized, which...

The main goal of this work is to model a homogeneous computer material with well-defined mechanical properties. To carry out the model material, an internal structure arranged in layers with different atom sizes is implemented using a simple interatomic law of Lennard-Jones type (LJ). We show that imposing an appropriate scaling law between the...

La presente invención tiene por objeto un procedimiento de adsorción de CO2 que consiste en hacer pasar un flujo de gas con una concentración determinada de CO2 a través de un lecho de polvo dispuesto sobre una placa porosa en una cámara de fluidización,

The time evolution of the problem of Electrohydrodynamic (EHD) convection in a liquid between two plates is analysed numerically. The equations are nondimensionalized using the ion drift velocity and the viscous time scales. Following the non-dimensionalisation of the respective model, two different techniques have been used to describe the...

Isotropic packings of cohesive disks in 2D are studied by discrete, stress-controlled numerical simulations. Depending on the assembling process and on whether contacts possess rolling resistance (RR), configurations form under low pressure P with varying solid fraction Φ and fractal dimension d F describing small scale correlations below some...

We have investigated the effect of vibrations on the stability of gas-fluidized beds of fine powders (particle size ~10 mm). The powder is uniformly fluidized by an adjustable gas flow that enables us to control the average solid volume fraction f0. The fluidized bed is then subjected to a vertical oscillatory motion of controlled amplitude and...

We report a novel experimental study on the jamming transition of dry fine powders with controlled attractive energy and particle size. Like in attractive colloids dry fine particles experience diffusionlimited clustering in the fluidlike regime. At the jamming threshold fractal clusters crowd in a metastable state at volume fractions depending...

We have investigated the self-diffusion in a stable gas-fluidized bed of fine powder. Two regimes have been observed: for gas velocities yg above the minimum fluidization velocity ym and below a critical gas velocity yc smaller than the minimum bubbling velocity yb the powder does not mix. Experimental measurements show the existence of yield...

We present measurements of the tensile strength as a function of the consolidation stress for a set of fine cohesive powders ~xerographic toners! of 12.7 mm particle size and with a range of concentration of submicron fumed silica as flow control additive. This additive is well known for its ability to control interparticle adhesion force....

An experimental investigation has been conducted to study corona discharge in a narrow tube. Narrow or capillary corona discharge (dis- charge tube diameter d = 1 to 20 mm) is used for many industrial applications such as flue gas cleaning corona induced plasma reactors, ion sources and electrohydrodynamic heat exchangers. In this work,...

Fluidized fractal clusters of fine particles display critical-like dynamics at the jamming transition, characterized by a power law relating consolidation stress with volume fraction increment. At a critical stress clusters are disrupted and there is a crossover to a logarithmic law resembling the phenomenology of soils. We measure _ _...

We investigate the dynamics of fine cohesive powders inside rotating drums. We show that these powders may be fluidized due to entrapment of ambient gas, and we determine the onset of fluidization. Experimental measurements on the bed expansion as a function of the rotation velocity have been performed. Drums of different diameters and fine...