A new method to measure particle turbulent dispersion using laser doppler anemometer

Arnason, G.; Stock, David

doi:10.1007/bf00261327

Cited by 8 publications

(7 citation statements)

References 4 publications

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“…An extensive review is not possible here, but it must be emphasized at the outset that almost all this work is confined to particle concentrations far below the range of interest from the point of view of particle transport systems. Many experiments have been described on vertical pipe flows with suspended spherical particles at mass loadings ranging up to about 6 (see, for example, So0 et al, 1960; Lee and Durst, 1982;Arnason and Stock, 1984;Tsuji et al, 1984). Mass loading is defined as the mass ratio of solids to gas, and values of 50 or higher are typically encountered in applications such as FCC risers.…”

Section: Dusty Gas Limitmentioning

confidence: 99%

Turbulent gas‐particle flow in vertical risers

1994

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Many experimental studies on the cross-sectional distribution of particles in vertical risers have revealed marked segregation of particles. These flows are inherently unsteady with large fluctuations in suspension density. In this article, we have analyzed the time-smoothed equations for the motion of dense suspensions to demonstrate the role of these fluctuations on the occurrence of segregation. It is shown that the particles will congregate in regions where the kinetic energy of fluctuations associated with the particles is small. In the context of transport of small particles such as FCC, a simplified model based on the mixture velocity can be constructed. A speculative K-e model based on this velocity is analyzed to illustrate the extent of segregation of particles afforded by unsteady fluctuations.

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Section: Dusty Gas Limitmentioning

confidence: 99%

Turbulent gas‐particle flow in vertical risers

1994

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“…It is less meaningful for turbulent shear flows, however, which is the case of turbulent pipe flow. A method is developed to allow local estimates for the diffusivity to be obtained when the turbulence is neither homogeneous nor isotropic [31]. If the flux is considered to be caused only by gradient diffusion (Fick's law), the particle dispersion coefficient at every radial location can be computed according to the following formula, except in regions where ∂C/∂r is near 0:…”

Section: Resultsmentioning

confidence: 99%

Particle-Laden Flow

Geurts¹,

Clercx²,

Uijttewaal³

2007

ERCOFTAC Series

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PrefaceThe dispersion of particles in a flow is of central importance in various geophysical and environmental problems. The spreading of aerosols and soot in the air, the growth and dispersion of plankton blooms in seas and oceans, or the transport of sediment in rivers, estuaries and coastal regions are striking examples.These problems are characterized by strong nonlinear coupling between several dynamical mechanisms such as convective sweeping, rotation, buoyancy, bio-physical influences and interactions between particles and fluid. As a result, processes on widely different length and time scales are simultaneously of importance. These range from Kolmogorov scales at which the flow at particle-scales is central, to much larger-scale structures that can be appreciated best via satellite observations. The multiscale nature of this challenging field motivated this colloquium that was organized by the recently established Dutch Platform for Geophysical and Environmental Fluid-mechanics (PGEF). The meeting took place at the University of Twente (the Netherlands), June 21-23, 2006. In total 55 participants from 13 different countries and 4 different continents contributed to the colloquium. The six keynote speakers provided reviews and recent research findings of areas that were central to the theme of the colloquium. These keynote lectures constituted the framework for the rest of the program, which contained 33 contributed papers, several of which are collected in this book.Issues related to the large-scale environmental aspects of particle-laden flows were addressed by considering turbulence modulation arising in high density clay-laden flows, and by focussing on transport processes in the stratosphere and its relevance to climate and weather predictions. Fundamental aspects of transport of particles formed the topic of the second day of the colloquium. Insights from experimental and computational research were combined to understand the distortion of flow in the neighborhood of embedded particles. Aspects of Lagrangian statistics in turbulence were discussed at length, addressing the dispersion of embedded point particles. Bridging the environ-VI Preface mental and the fundamental aspects of particle-laden flows was the topic of the final day of the colloquium. The Lagrangian dispersion of particles in the context of their environmental setting was presented. The closing lecture provided a synopsis of transport processes in particle-laden flow in which possibilities of multi-resolution, multi-physics modeling and monitoring were discussed.The colloquium on particle-laden flow was organized under the auspices of EUROMECH, the European Mechanics Society, and the Universities of Technology of Delft, Eindhoven and Twente. It was supported financially by a number of institutions: ERCOFTAC (European Research Council On Flow, Turbulence and Combustion), COST Action P20 'LES-AID' (COoperation in the field of Science and Technology), the Netherlands foundation for fundamental research of matter (FOM), the Netherland...

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“…Chen and Crowe [74] simulated the experiment in a pipe flow of Arnason [75,76] and for the near isotropic homogeneous grid turbulence in Snyder and Lumley's experiments [15]; however they calibrated the model by changing the constant C µ to fit the last experiment. Durst et al [77] developed a simple EIM based on the previous work of Gosman and Ioannides [67,68], and the equation of motion was solved analytically for short time steps.…”

Section: Historical Backgroundmentioning

confidence: 99%

“…Durst et al [77] developed a simple EIM based on the previous work of Gosman and Ioannides [67,68], and the equation of motion was solved analytically for short time steps. Milojevic [78] optimized the model for various test flow configurations [15,16,75,76]. It was modified for particulate two-phase systems with a size distribution by Sommerfeld and coworkers [79,80].…”

Section: Historical Backgroundmentioning

confidence: 99%

An Overview of the Lagrangian Dispersion Modeling of Heavy Particles in Homogeneous Isotropic Turbulence and Considerations on Related LES Simulations

Huilier

2021

Fluids

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Particle tracking is a competitive technique widely used in two-phase flows and best suited to simulate the dispersion of heavy particles in the atmosphere. Most Lagrangian models in the statistical approach to turbulence are based either on the eddy interaction model (EIM) and the Monte-Carlo method or on random walk models (RWMs) making use of Markov chains and a Langevin equation. In the present work, both discontinuous and continuous random walk techniques are used to model the dispersion of heavy spherical particles in homogeneous isotropic stationary turbulence (HIST). Their efficiency to predict particle long time dispersion, mean-square velocity and Lagrangian integral time scales are discussed. Computation results with zero and no-zero mean drift velocity are reported; they are intended to quantify the inertia, gravity, crossing-trajectory and continuity effects controlling the dispersion. The calculations concern dense monodisperse spheres in air, the particle Stokes number ranging from 0.007 to 4. Due to the weaknesses of such models, a more sophisticated matrix method will also be explored, able to simulate the true fluid turbulence experienced by the particle for long time dispersion studies. Computer evolution and performance since allowed to develop, instead of Reynold-Averaged Navier-Stokes (RANS)-based studies, large eddy simulation (LES) and direct numerical simulation (DNS) of turbulence coupled to Generalized Langevin Models. A short review on the progress of the Lagrangian simulations based on large eddy simulation (LES) will therefore be provided too, highlighting preferential concentration. The theoretical framework for the fluid time correlation functions along the heavy particle path is that suggested by Wang and Stock.

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A new method to measure particle turbulent dispersion using laser doppler anemometer

Cited by 8 publications

References 4 publications

Turbulent gas‐particle flow in vertical risers

Turbulent gas‐particle flow in vertical risers

Particle-Laden Flow

An Overview of the Lagrangian Dispersion Modeling of Heavy Particles in Homogeneous Isotropic Turbulence and Considerations on Related LES Simulations

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