Measurements of collisional properties of spheres using high-speed video analysis

Labous, Laurent; Rosato, Anthony; Davé, Rajesh N.

doi:10.1103/physreve.56.5717

Cited by 190 publications

(129 citation statements)

References 31 publications

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“…When the impact velocity v is large (v 5 m/s [10]), the colliding particles deform fully plastically and r ∝ v −1/4 , as reported experimentally [11,12,13,14] and theoretically [10,12,15,16]. When v 0.1 m/s [10], the deformations are elastic with mainly viscoelastic dissipation, and 1 − r ∝ v 1/5 , as reported experimentally [14,17,18] and theoretically [17,19]. Such velocity-dependent restitution coefficient models have recently shown to be important in numerical [20,21,22,23,24,25,26] and experimental [18,27] studies.…”

Section: The Variable Coefficient Of Restitutionmentioning

confidence: 90%

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Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

McNamara

Falcon

2008

Powder Technology

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We report two-dimensional simulations of strongly vibrated granular materials without gravity. The coefficient of restitution depends on the impact velocity between particles by taking into account both the viscoelastic and plastic deformations of particles, occurring at low and high velocities respectively. Use of this model of restitution coefficient leads to new unexpected behaviors. When the number of particles N is large, a loose cluster appears near the fixed wall, opposite the vibrating wall. The pressure exerted on the walls becomes independent of N , and linear in the vibration velocity V , quite as the granular temperature. The collision frequency at the vibrating wall becomes independent of both N and V , whereas at the fixed wall, it is linear in both N and V . These behaviors arise because the velocity-dependent restitution coefficient introduces a new time scale related to the collision velocity near the cross over from viscoelastic to plastic deformation.

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Section: The Variable Coefficient Of Restitutionmentioning

confidence: 90%

“…For more informations on restitution coefficient measurements, see Ref. [11,12,13,14,17,18,27,28,29].…”

Section: The Variable Coefficient Of Restitutionmentioning

confidence: 99%

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

McNamara

Falcon

2008

Powder Technology

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“…For the particle-particle impact experiments, in contrast to the above category of devices, two particles collide without any rigid tool according to (Fig. 8b) [15,20,55,59]. This type of stressing occurs in fluidized bed granulation and comminution.…”

Section: Measurement Of the Restitution Coefficient Of A Granulementioning

confidence: 99%

“…7b. For elastic-plastic behaviour during the impact, the restitution coefficient is in the range of 0 < e < 1, see examples in [5,15,16,20,23,28,34,55,59,60,71,76,83,85,88,91,92].…”

Section: Measurement Of the Restitution Coefficient Of A Granulementioning

confidence: 99%

Energy absorption during compression and impact of dry elastic-plastic spherical granules

et al. 2010

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The discrete modelling and understanding of the particle dynamics in fluidized bed apparatuses, mixers, mills and others are based on the knowledge about the physical properties of particles and their mechanical behaviour during slow, fast and repeated stressing. In this paper model parameters (modulus of elasticity, stiffness, yield pressure, restitution coefficient and strength) of spherical granules ( γ -Al 2 O 3 , zeolites 4A and 13X, sodium benzoate) with different mechanical behaviour have been measured by single particle compression and impact tests. Starting with the elastic compression behaviour of granules as described by Hertz theory, a new contact model was developed to describe the force-displacement behaviour of elastic-plastic granules. The aim of this work is to understand the energy absorption during compression (slow stressing velocity of 0.02 mm/s) and impact (the impact velocity of 0.5-4.5 m/s) of granules. For all examined granules the estimated energy absorption during the impact is found to be far lower than that during compression. Moreover, the measured restitution coefficient is independent of the impact velocity in the examined range and independent of the load intensity by compression (i.e. maximum compressive load). In the case of repeated loading with a constant load amplitude, the granules show cyclic hardening with increasing restitution coefficient up to a certain saturation in the plastic deformation. A model was proposed to describe the increase of the contact stiffness with the number of cycles. When the load amplitude is subsequently increased, further plastic deformation takes place and the restitution coefficient strongly decreases.

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“…Several analytical and semi-empirical models have been developed to evaluate µ and e w in terms of flow parameters such as the impact velocity, impact angle, particle spin and the particle and wall properties [25][26][27][28][29]. While it has been shown that the frictional coefficient significantly affects the collision regime (sliding/non-sliding) [25], fluidization predictions are not sensitive to e w in the range 0.7-1.0 [1,30].…”

Section: Introductionmentioning

confidence: 99%

Eulerian–Eulerian simulation of dense solid–gas cylindrical fluidized beds: Impact of wall boundary condition and drag model on fluidization

et al. 2015

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Modeling the hydrodynamics of dense-solid gas flows is strongly affected by the wall boundary condition and in particular, the specularity coefficient φ which characterizes the tangential momentum transfer from the particles to the wall. The focus of this study is to investigate the impact of φ on the fluidization hydrodynamics using a fully Eulerian description of the solid and gas phases in 3D cylindrical coordinates. In order to quantify this impact, tools for characterizing the bubbling dynamics and solids circulation are developed and applied to both lab-scale (diameters 10 cm and 14.5 cm) and pilot-scale (diameter 30 cm) cylindrical beds. Comparison of simulation predictions with experimental data for different fluidization regimes and particle properties suggests that values of φ in the range [0.01,0.3] are suitable for simulating most dense solid-gas flows of practical interest. It is also shown that for this range of φ, the fluidization hydrodynamics are not significantly dependent on the choice of φ especially as the bed diameter is increased. Additionally, 3D validation of the variable φ model by Li and Benyahia [1] shows the bubble diameter predictions to be in excellent agreement with experiment and the average value of φ predicted within the range [0.01,0.3]. Quantifying the impact of φ and establishing an appropriate range is not only important for accurate simulations at both lab and pilot scales but also validation of models and sub-models for a better understanding of the fluidization phenomenon. Finally, a comparison of the Gidaspow and Syamlal-O'Brien gas-solids drag model shows that the former is more applicable to homogeneous bubbling fluidization (U/U mf <4) while the latter is only suitable for high velocities (U/U mf >4) associated with larger bubbles and slugs.

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Measurements of collisional properties of spheres using high-speed video analysis

Cited by 190 publications

References 31 publications

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

Energy absorption during compression and impact of dry elastic-plastic spherical granules

Eulerian–Eulerian simulation of dense solid–gas cylindrical fluidized beds: Impact of wall boundary condition and drag model on fluidization

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