Effect of viscosity on the avalanche dynamics and flow transition of wet granular matter

Kasper, Jens Henry; Magnanimo, Vanessa; Jong, Sjoerd de; Beek, Arjan; Jarray, Ahmed

doi:10.1016/j.partic.2020.12.001

Cited by 14 publications

(30 citation statements)

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“…Recent studies have shown that the discrete-element method (DEM) is a powerful tool for simulating dry granular mixtures 1,2 ; however, the extension of DEM to wet granular mixtures has proved challenging. [3][4][5] Several studies have concluded that the inclusion of even small amounts of liquid, drastically change the rheology of the granular flow. 6 Many studies have investigated the macroscopic nature of these wet granular flows.…”

Section: Introductionmentioning

confidence: 99%

“…6 Many studies have investigated the macroscopic nature of these wet granular flows. 3,7,8 This study examines the microscopic dynamics of collisions of wet particles.The regime we consider has a thin layer of interstitial liquid between the spheres. The interstitial liquid between the spheres during the collision forms a pendular bridge and we refer to these systems as being in the pendular regime.…”

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confidence: 99%

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A comparison of pendulum experiments and discrete‐element simulations of oblique collisions of wet spheres

et al. 2022

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Oblique collisions of two spherical particles coated with a thin layer of viscous liquid are considered. Experimental measurements are performed using particle tracking velocimetry and the results are compared to viscous force and capillary force models via numerical simulation using the discrete‐element method. Comprehensive experimental data for collisions with an impact angle between 0° and 60° are presented to ensure future models can be rigorously validated. Collisions are characterized by the normal Stokes' number (a dimensionless ratio of normal inertial forces to normal viscous forces), and the normal coefficient of restitution (a dimensionless ratio of postcollisional normal velocity to precollisional normal velocity). Good agreement was found between the models and the experiments at high Stokes' number, where the models are dominated by the normal components. As the tangential forces become more significant (i.e., at low to medium Stokes' number, and high collision angle), agreement between the simulations and experiments is poorer. Furthermore, the models predict a decreasing rotational velocity with increasing Stokes' number past some critical Stokes' number. A coefficient of friction term was implemented and found to improve agreement for the rotational velocity postcollision.

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Section: Introductionmentioning

confidence: 99%

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A comparison of pendulum experiments and discrete‐element simulations of oblique collisions of wet spheres

et al. 2022

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“…Hysteresis in suspensions is shown to be of a frictional rheological nature and caused by interparticle friction. In [39,40], hysteresis transition of motion modes of the cohesive granular filler was investigated numerically by DEM with experimental testing, taking into account cohesion. It was found that with increasing cohesion, the range of periodic collapse avalanches decreases and the transition to the steady continuous mode is accelerated.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

Deineka

Naumenko

2022

EEJET

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The qualitative nature and quantitative parameters of motion instability of a two-fraction granular filler of a rotating drum were determined. The factors of motion instability and key parameters of the oscillating system were identified and their influence on the self-excitation of pulsed self-oscillations was estimated. Two continuous and one periodic steady-state modes of filler motion were found. Periodic self-oscillations due to the development of instability during the transition from continuous circulation mode to the wall layer mode were revealed. As factors of motion instability, filler dilatancy and damping effect of fine fraction particles on the pulsed interaction of coarse fraction particles were taken. It turned out that the main key parameter of the oscillating system is the drum speed, which determines a change in dilatancy. The increase in instability is realized as a reduction of the bifurcation values of speed and dilatancy. Other key parameters are the content of the fine fraction in the filler κff and the filling degree of the chamber κlf, the growth of which increases the self-oscillating instability. The features of the oscillatory system are the relaxation type, discontinuous nature of self-oscillations and hard self-excitation mode under bistability. The discontinuous character and oscillatory hysteresis increase with decreasing κff and κlf. The limit values of the dynamic motion parameters corresponding to the conditions of self-excitation of self-oscillations in the absence and presence of fine fraction were determined: 0.96–1.11 and 0.218–0.382 for the bifurcation value of relative speed, 0.745–0.855 and 0.24–0.322 for the bifurcation value of dilatancy. The effects found make it possible to substantiate the parameters of the self-oscillating process of processing polygranular materials in drum-type machines.

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“…Increased convexity of the free surface shape, the increase in the thickness of the shear layer, and the transition from shear circulation to rolling have been established. The authors of [4,5] employed DEM and experimentally detected the transition of the fill movement mode with periodic collapse into continuous rolling. A decrease in the mutual pushing of particles due to the dissipation of kinetic energy with increased solidity was established.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Establishing the conditions for the formation of a near-wall layer of solid granular fill of a rotating drum

Naumenko¹,

Deineka²,

Myronenko³

2021

EEJET

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This paper reports the assessment of the influence of dynamic motion parameters on the formation and disappearance at the cylindrical surface of the chamber of the rotating drum of the near-wall layer of non-loose granular fill. Based on the results of experimental visualization of the flow, the effect of solidity on the behavior of granular fill was revealed. The hydrodynamic effect of fill quasi-liquefaction under the action of solidity has been established, which involves the occurrence of a connecting interaction between adjacent layers and the surface of the chamber. Conversion of shear circulation flow to homogeneous dense clustered stream with slipping and rolling without relative movement of particles was detected. The hydrodynamic characteristics of circulation flow transition to the near-wall layer mode during rotation acceleration have been defined. Such a transition is implemented by smoothly increasing the thickness of the layer when the rest of the fill is circulated at the bottom of the chamber. The effect of the rheological hysteresis of the movement of the rotating chamber fill, caused by quasi-liquefaction of non-loose granular environment, has been established. The effect implies exceeding the speed limit ωfl in the formation of a near-wall layer, at rotation acceleration, above the boundary ωdl of the layer disappearance when the rotation slows down. The manifestation of hysteresis mainly increases with an increase in Reynolds number. The intensity of increased hysteresis manifestation increases with a decrease in the degree of filling the chamber. The value of the Froud number for the ωfl and ωdl boundaries increases with the increase in Re. It has been established that at the relative particle size of the dispersed fill ψdc≈(0.065–1.04)·10‑3 and Re=30–500, Fr=1–2.9, for the ωfl boundary, and Fr=0.5–1.4, for the ωdl boundary. The Fr value for the ωfl limit was found to exceed this value for the ωdl boundary by 1.6–2.1 times. The established effects make it possible to substantiate the rational parameters for the grinding process in drum-roll mills

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Effect of viscosity on the avalanche dynamics and flow transition of wet granular matter

Cited by 14 publications

References 50 publications

A comparison of pendulum experiments and discrete‐element simulations of oblique collisions of wet spheres

A comparison of pendulum experiments and discrete‐element simulations of oblique collisions of wet spheres

Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

Establishing the conditions for the formation of a near-wall layer of solid granular fill of a rotating drum

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