Particle dynamics in a dense vibrated fluidized bed as revealed by diffusing wave spectroscopy

Živković, Vladimir; Biggs, Mark J.; Glass, Donald; Pagliai, P.; Buts, A.

doi:10.1016/j.powtec.2007.12.007

Cited by 20 publications

(30 citation statements)

References 47 publications

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“…9 shows variation of height-averaged velocity fluctuations with superficial velocity. The velocity fluctuations are the same order of magnitude as the driving velocity as observed in the other FB systems considered by us to date (Xie et al, 2006;Biggs et al, 2008a,b;Zivkovic et al, 2008), and increase with superficial velocity up to a maximum at U 0 = 7.5 mm/s. Batchelor (1988) hypothesized that for a uniform FB, the particle velocity fluctuations can be related to the mean particle velocity averaged over the FB cross-section, v, by where H() is a function of the solid fraction only.…”

Section: Spatial Variation Of Granular Temperaturesupporting

confidence: 80%

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Granular temperature in a liquid fluidized bed as revealed by diffusing wave spectroscopy

Živković¹,

Biggs²,

Glass³

et al. 2009

Chemical Engineering Science

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We report granular temperature and solid fraction fields for a thin rectangular bed (20×200 mm crosssection and 500 mm high) of glass particles (mean diameter of 165 m and density of 2500 kg/m 3 ) fluidized by water for superficial velocities ranging from 0.05U t , which is approximately double the minimum fluidization velocity, to 0.49U t , where U t is the particle terminal velocity estimated by fitting the Richardson-Zaki correlation to the bed expansion data. At superficial velocities below 0.336U t , the solid fraction and granular temperature are uniform throughout the bed. At higher superficial velocities, the solid fraction tends to decrease with height above the distributor, whilst the granular temperature first increases to a maximum before decaying towards the top of the bed. Correlation of the mean granular temperature with the mean solid fraction and the local granular temperature with the local solid fraction both suggest that the granular temperature in the liquid fluidized bed can be described solely in terms of the solid fraction. The granular temperature increases monotonically with solid fraction to a maximum at ≈ 0.18 where it then decreases monotonically as approaches the close-packed limit.

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Section: Spatial Variation Of Granular Temperaturesupporting

confidence: 80%

“…DWS (Weitz and Pine, 1993), which has now been applied extensively in the study of particle dynamics in various dense granular systems (Menon and Durian, 1997a,b;Xie et al, 2006;Biggs et al, 2008a,b;Zivkovic et al, 2008) was used here in the transmission mode as illustrated in Fig. 1b.…”

Section: Diffusing Wave Spectroscopymentioning

confidence: 99%

Granular temperature in a liquid fluidized bed as revealed by diffusing wave spectroscopy

Živković¹,

Biggs²,

Glass³

et al. 2009

Chemical Engineering Science

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“…However, the coexistence of a fluid-like granular gas with a solid-like packing also occurs in many other systems, for example during avalanche flow on inclined planes or in vibrated containers, see Refs. [28,30,32,34,[55][56][57][58][59] and references therein. Methods developed for granular gases have even found application in the dynamics of animal encounters, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Towards dense, realistic granular media in 2D

Luding¹

2009

Nonlinearity

133

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The development of an applicable theory for granular matter -with both qualitative and quantitative value -is a challenging prospect, given the multitude of states, phases and (industrial) situations it has to cover. Given the general balance equations for mass, momentum, and energy, the limiting case of dilute and almost elastic granular gases, where kinetic theory works perfectly well, is the starting point.In most systems, low density coexists with very high density, where the latter is an open problem for kinetic theory. Furthermore, many additional non-linear phenomena and material properties are important in realistic granular media, involving, e.g.: (i) multi-particle interactions and elasticity (ii) strong dissipation, (iii) friction, (iv) long-range forces and wet contacts (v) wide particle size-distributions, and (vi) various particle shapes. Note that, while some of these issues are more relevant for high density, others are important for both low and high densities; some of them can be dealt with by means of kinetic theory, some can not. This paper is a review of recent progress towards more realistic models for dense granular media in 2D, even though most of the observations, conclusions, and corrections given are qualitatively true also in 3D. Starting from an elastic, frictionless and monodisperse hard sphere gas, the (continuum) balance equations of mass, momentum and energy are given. The equation of state, the (Navier-Stokes level) transport coefficients and the energy-density dissipation rate are considered. Several corrections are applied to those constitutive material laws -one by one -in order to account for the realistic physical effects and properties listed above.

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“…We have used this non-invasive technique to study extensively particle dynamics and the granular temperature in a variety of dense fluidized beds: gas- [14], liquid- [15] fluidized beds (FBs), and dry- [16,17] and submerged- [18] vibrated beds. Using the liquid-FB work as an example, we demonstrate here that kinetic theory of granular flow formulas can be used with DWS-derived granular temperature to obtain the granular pressure and viscosity.…”

Section: Introductionmentioning

confidence: 99%