Localized fluidization in granular materials: Theoretical and numerical study

Montellà, Eduard Puig; Toraldo, Marcella; Chareyre, Bruno; Sibille, Luc

doi:10.1103/physreve.94.052905

Cited by 23 publications

(17 citation statements)

References 23 publications

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“…Eventually, the height of the fluidized zone increases with the injection rate, until it reaches the top of the granular layer (chimney regime). Numerical simulations were found to match qualitatively with available experimental data [8]. Crude simplifications are required to find an analytical solution due to the nonlinear process.…”

Section: Introductionmentioning

confidence: 70%

“…Then, following [8], the key part of the theoretical modeling is to determine the spatial distribution of pore pressure within the specimen to identify the locations in which it reaches (or exceeds) the total stress such that:…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Assuming Darcy's flow in a rigid porous layer (figure 1), the pressure at any point of the specimen can be obtained as [8]:…”

Section: Theoretical Modelmentioning

confidence: 99%

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From continuum analytical description to discrete numerical modelling of localized fluidization in granular media

Montellà¹,

Toraldo²,

Sibille³

2017

EPJ Web Conf.

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Abstract. We present analytical and numerical results on localized fluidization within a granular layer subjected to a local injection of fluid. As the injection rate increases the three different regimes previously reported in the literature are recovered: homogeneous expansion of the bed, fluidized cavity in which fluidization starts developing above the injection area, and finally the chimney of fluidized grains when the fluidization zone reaches the free surface. The analytical approach is at the continuum scale, based on Darcy's law and Therzaghi's effective stress principle. It provides a good description of the phenomenon as long as the porosity of the granular assembly remains relatively homogeneous. The numerical approach is at the particle scale based on the coupled DEM-PFV method. It tackles the more heterogeneous situations which occur at larger injection rates. A direct link is evidenced between the occurrence of the different regimes of fluidization and the injection aperture. Finally, the merging of chimneys in case of two injection points is investigated.

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Section: Introductionmentioning

confidence: 70%

Section: Theoretical Modelmentioning

confidence: 99%

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From continuum analytical description to discrete numerical modelling of localized fluidization in granular media

Montellà¹,

Toraldo²,

Sibille³

2017

EPJ Web Conf.

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“…The motion forms a fluidization chimney when it reaches the top of the bed. The fluid velocity influences the chimney diameter [15,16].…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

An experimental study of fluidization post impinging fluid in granular bed for breaking sedimentation

Yudiyanto¹,

Wardana

Hamidi

et al. 2020

EEJET

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The impinging fluid can be used as a prevention of sedimentation in the flow of the pipe and the mixing process. Sedimentation is a problem that often occurs in fluid transportation and fluidization. Granular material behavior due to impinging is a phenomenon that is rarely studied. This condition is difficult to observe due to the position of complex fluid movements in the bed. The study tries to find the behavior of fluidization at various granular sizes. The effect of impinging into the granular bed has been observed with experimental studies. Hele-Shaw cell is used as equipment for the observation process. The glass sand is used as a medium of fluidization. The high-speed fluid is injected into a granular bed in a short time. Granular material moves because of the pressure impinging as fluidization. The motion of the granular material is observed by a camera to determine the behavior of the granular material. The primary outcome of the present study is the identification of two very distinct regimes. There are two types of post-impinging fluidization. The first type is the fluid cavity and fluidization. The condition starts with a fluid cavity expansion and continues with the fluidization process. The fluid cavity occurs because the fluid shock pressure pushes the granular material upward. Granular bonds hold the particles' connection and form a cavity. Fluidization after cavity expansion is a settling motion that is influenced by gravity, buoyancy, drag, and granular bonds. The other type is a local fluidized state. The limit for the occurrence of fluid cavity and fluidization is observed with the Reynolds number of impinging. The Reynolds number of impinging is calculated by the velocity of entry of the shock fluid in the granular and multiplied size of the particles divided by the viscosity. The fluid cavity post-impinging occurs at the Reynolds number of the impinging process less than 4,000 (laminar and transition flow area). The local fluidized state has Re of impinging more than 4,000, and the fluidization follows the flow and disappears immediately. This condition causes the bonding of the granules cannot maintain the agglomeration of the granules

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“…Nevertheless, only a few of these studies have focused on localized fluidization. Apart from a very recent work based on Computational Fluid Dynamics (CFD) computation including granular kinetic theory with Eulerian approach [43], all other previous numerical investigations used a discrete particle approach to model related systems such as multiple spout-fluidized beds [29], gas-fluidized bed by DEM-CFD algorithm [44], fluidization of a cohesionless particulate bed by a localized fluid influx [45,46], or even partial fluidization of a cohesive soil layer by DEM-LBM simulation [47,48]. As in these two latter studies, combining the discrete element method and the lattice Boltzmann method appears to be a highly efficient strategy for simulating fluidgrain coupling in relation to soil mechanic issues [49][50][51] including porous flow [52], immersed granular flows [53,54], and soil erosion [55][56][57].…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional numerical simulation of chimney fluidization in a granular medium using a combination of discrete element and lattice Boltzmann methods

Ngoma¹,

Philippe²,

Bonelli³

et al. 2018

Phys. Rev. E

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We present here a numerical study dedicated to the fluidization of a submerged granular medium induced by a localized fluid injection. To this end, a two-dimensional (2D) model is used, coupling the lattice Boltzmann method (LBM) with the discrete element method (DEM) for a relevant description of fluid-grains interaction. An extensive investigation has been carried out to analyze the respective influences of the different parameters of our configuration, both geometrical (bed height, grain diameter, injection width) and physical (fluid viscosity, buoyancy). Compared to previous experimental works, the same qualitative features are recovered as regards the general phenomenology including transitory phase, stationary states, and hysteretic behavior. We also present quantitative findings about transient fluidization, for which several dimensionless quantities and scaling laws are proposed, and about the influence of the injection width, from localized to homogeneous fluidization. Finally, the impact of the present 2D geometry is discussed, by comparison to the real three-dimensional (3D) experiments, as well as the crucial role of the prevailing hydrodynamic regime within the expanding cavity, quantified through a cavity Reynolds number, that can presumably explain some substantial differences observed regarding upward expansion process of the fluidized zone when the fluid viscosity is changed.

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Localized fluidization in granular materials: Theoretical and numerical study

Cited by 23 publications

References 23 publications

From continuum analytical description to discrete numerical modelling of localized fluidization in granular media

From continuum analytical description to discrete numerical modelling of localized fluidization in granular media

An experimental study of fluidization post impinging fluid in granular bed for breaking sedimentation

Two-dimensional numerical simulation of chimney fluidization in a granular medium using a combination of discrete element and lattice Boltzmann methods

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