Segregation of granular materials in bounded heap flow: A review

Fan, Yunyun; Jacob, Karl; Freireich, Ben; Lueptow, Richard M.

doi:10.1016/j.powtec.2017.02.026

Cited by 69 publications

(37 citation statements)

References 116 publications

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“…This again indicates that using W = rΘ is a reasonable modification of the JFP scaling for the frictional wedge geometry. We further note that JFP indicate that Equations (2) and (3) are valid for q*/W* 5/2( 1,21 which is the case for the data presented inFigure 12b,c. The collapse of the data in Figures 12b,c for all radial and azimuthal locations throughout the frictional wedge demonstrates that the JFP scalings describe the local kinematics.…”

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confidence: 53%

Section: Introductionmentioning

confidence: 99%

“…Cylindrical silos are among the oldest and most commonly used industrial container designs for the storage of granular solids, and, accordingly, they are prevalent in the agricultural and chemical industries. 1 The two most important flows in silos correspond to material filling and material discharge. [2][3][4][5][6][7][8][9][10][11] Granular heap flow during filling is bounded by the silo walls; consequently, the geometry of the containing vessel imposes a streamwise length scale on the flow.…”

Section: Introductionmentioning

confidence: 99%

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Granular flow in a wedge‐shaped heap: Velocity field, kinematic scalings, and segregation

et al. 2020

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Free surface granular flows in bounded axisymmetric geometries are poorly understood. Here, we consider the kinematics and segregation of size‐bidisperse flow in a rising conical heap by characterizing the flow of particles in a wedge‐shaped silo with frictional sidewalls using experiments and discrete‐element‐method simulations. We find that the streamwise velocity is largest at the wedge centerline and decreases near the sidewalls, and that velocity profiles in the depthwise and spanwise directions are self‐similar. For segregating size bidisperse mixtures, the boundary between small and large particles deposited on the heap is significantly further upstream at the sidewalls than at the centerline, indicating that measurements taken at transparent sidewalls of quasi‐2D or wedge‐shaped heaps are unrepresentative of an axisymmetric heap. The streamwise velocity and flowing layer depth locally satisfy the scaling relation of Jop et al (J Fluid Mech. 2005;541:167‐192) when modified to account for the wedge geometry, highlighting the influence of wall friction on the flow.

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confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Granular flow in a wedge‐shaped heap: Velocity field, kinematic scalings, and segregation

et al. 2020

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“…Segregation of flowing granular materials, differing in properties such as density or size, has been studied both experimentally and theoretically in a number of canonical geometries including chutes [1,2], quasi-two-dimensional (2D) bounded heaps [3], and annular shear cells [4], where the underlying flow field is relatively simple and develops easily predicted segregation patterns. However, the situation can be more complex when the chaotic dynamics of the underlying flow field interacts with segregation, as can occur in quasi-2D tumblers [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Pattern formation in a fully three-dimensional segregating granular flow

Umbanhowar

Ottino

et al. 2019

Phys. Rev. E

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Segregation patterns of size-bidisperse particle mixtures in a fully-three-dimensional flow produced by alternately rotating a spherical tumbler about two perpendicular axes are studied over a range of particle sizes and volume ratios using both experiments and a continuum model. Pattern formation results from the interaction of size segregation with chaotic regions and non-mixing islands of the flow. Specifically, large particles in the flowing surface layer are preferentially deposited in non-mixing islands despite the effects of collisional diffusion and chaotic transport. The protocol-dependent structure of the unstable manifolds of the flow surrounding the non-mixing islands provides further insight into why certain segregation patterns are more robust than others.

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“…While most previous studies of quasi-2D bounded heap formation have considered steady feed rates exclusively, e.g. [1][2][3][4][5][6][7], recent work with size bidisperse mixtures of spherical granular particles fed onto a quasi-2D bounded heap under alternating feed rates shows dramatic changes to the segregation pattern, indicating the existence of complex transient flows [8]. This work raises the question of how granular flows relax to steady-state following a change to a control parameter such as the feed rate.In bounded heap flows, particles travel down the surface in a thin flowing layer over a static bed with a rising free surface inclined at an angle determined by particle properties (e.g., shape and friction), the sidewall gap, and the feed rate [4,9].…”

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Transient response in granular quasi-two-dimensional bounded heap flow

et al. 2017

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We study the transition between steady flows of noncohesive granular materials in quasi-two-dimensional bounded heaps by suddenly changing the feed rate. In both experiments and simulations, the primary feature of the transition is a wedge of flowing particles that propagates downstream over the rising free surface with a wedge front velocity inversely proportional to the square root of time. An additional longer duration transient process continues after the wedge front reaches the downstream wall. The entire transition is well modeled as a moving boundary problem with a diffusionlike equation derived from local mass balance and a local relation between the flux and the surface slope.

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Segregation of granular materials in bounded heap flow: A review

Cited by 69 publications

References 116 publications

Granular flow in a wedge‐shaped heap: Velocity field, kinematic scalings, and segregation

Granular flow in a wedge‐shaped heap: Velocity field, kinematic scalings, and segregation

Pattern formation in a fully three-dimensional segregating granular flow

Transient response in granular quasi-two-dimensional bounded heap flow

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