Granular Flows Modeling and Simulation

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics and Hydrodynamics".

Deadline for manuscript submissions: closed (15 December 2022) | Viewed by 12405

Special Issue Editors


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Guest Editor
Faculty of Science and Technology, Free University of Bozen-Bolzano, Universitätsplatz 5–piazza Università 5, 39100 Bozen-Bolzano, Italy
Interests: fluid mechanics; granular flows; granular segregation; debris flow; mudflow; snow avalanches; non-intrusive experimental techniques; river restoration; industrial processes; energy conversion

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Guest Editor
GPEM laboratory, Materials and Structures department, The French institute for science and technology for transport, development and networks (IFSTTAR), Allée des Ponts et Chaussées, 44344 Bouguenais cedex, France
Interests: granular flows; particle breakage; size/density segregation; discrete element simulation; corse graining techniques; industrial applications (moving bed reactors, granulators, driers, sorters)

Special Issue Information

Dear Colleagues,

A proper understanding of granular systems is strategic for many research areas (e.g., physics, mathematics, engineering, chemistry), for industrial applications (e.g., energy conversion, food technology, pharmaceutical production, construction engineering) and for environmental applications (e.g., sediment transport, snow avalanches, debris flow, desertification, river restoration).

Although several approaches have been successfully proposed and employed for the description of granular flow, some aspects are still unclear and deserve further investigations. Among others, we can mention modeling particle interactions, describing size and density segregation and their influence on flow properties, developing reliable and efficient mathematical models that incorporate the rheology close to interfaces (walls, free surface, intruders, ...), improving experimental techniques in order to resolve single grain motions, and measuring velocity and concentration fluctuations in the whole flow domain. Moreover, the prediction of some specific flow conditions can be very challenging. This may be due to the interactions between the particles and the interstitial fluid, or to the possible coexistence of rheological regimes, ranging from quasi-static equilibrium to collision-dominated flow.

The goal of this special issue is to gather high-quality papers relevant to granular flows that address aspects of theory, experiment and numerical simulation. Contributions aimed at comparing existing models or giving novel interpretations of previous results available in the literature are highly welcome.

Prof. Michele Larcher
Dr. Riccardo Artoni
Guest Editors

Manuscript Submission Information

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Keywords

  • granular flows
  • granular segregation
  • geophysical flows
  • industrial applications
  • interface rheology
  • discrete element simulation
  • numerical models
  • non-intrusive experimental methods

Published Papers (5 papers)

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Research

13 pages, 1089 KiB  
Article
Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases
by James T. Jenkins and Michele Larcher
Water 2023, 15(14), 2629; https://doi.org/10.3390/w15142629 - 20 Jul 2023
Viewed by 701
Abstract
Kinetic theory is used to propose and solve boundary value problems for fully developed, steady, dense gravity-driven flows of mixtures composed of identical inelastic spheres and water over both inclined erodible beds and rigid, bumpy bases confined by vertical sidewalls. We solve the [...] Read more.
Kinetic theory is used to propose and solve boundary value problems for fully developed, steady, dense gravity-driven flows of mixtures composed of identical inelastic spheres and water over both inclined erodible beds and rigid, bumpy bases confined by vertical sidewalls. We solve the boundary value problems assuming values of the mass density and of the size of the spheres typical of natural materials and show the numerical solutions for the profiles of the mean velocities of the particles and fluid, the intensity of the particle velocity fluctuations, and the granular concentration. In addition, we indicate how the features of the grain velocity fluctuations profile would influence segregation in three situations when the particle phase consists of two sizes of spheres: (1) the spheres are of the same material, and only gradients of temperature influence their segregation; (2) the mass densities of the material of the spheres are such that only gravity influences segregation; and (3) the mass densities are such that the coefficients of the temperature gradients and gravity segregation mechanisms are equal. For spheres of the same material, over a rigid bumpy base, the concentration of larger spheres increases from zero at the bed to the maximum value at the top of the flow; while over an erodible bed, this concentration has its maximum value at both the bed and the top of the flow. Full article
(This article belongs to the Special Issue Granular Flows Modeling and Simulation)
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19 pages, 2059 KiB  
Article
Modelling Intense Combined Load Transport in Open Channel
by Václav Matoušek
Water 2022, 14(4), 572; https://doi.org/10.3390/w14040572 - 14 Feb 2022
Cited by 3 | Viewed by 1437
Abstract
Granular flow is modelled under the following conditions: Steady-state uniform turbulent open-channel solid–liquid flow carrying combined load at high solids concentration above a plane mobile bed. In the combined load, a portion of transported particles is transported as collisional bed load and the [...] Read more.
Granular flow is modelled under the following conditions: Steady-state uniform turbulent open-channel solid–liquid flow carrying combined load at high solids concentration above a plane mobile bed. In the combined load, a portion of transported particles is transported as collisional bed load and the rest as suspended load supported by carrier turbulence. In our modelling approach, we consider one-dimensional flow and take into account a layered structure of the flow with the intense combined load. Principles of kinetic theory of granular flow are employed together with the mixing-length theory of flow turbulence in order to predict distributions of solids concentration and velocity in sediment-water flow of the given flow depth and longitudinal slope in an open channel. Components of the model are tested and calibrated by results of our laboratory experiments with lightweight sediment in a recirculating tilting flume. Full article
(This article belongs to the Special Issue Granular Flows Modeling and Simulation)
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19 pages, 7738 KiB  
Article
Calibration of Adjustment Coefficient of the Viscous Boundary in Particle Discrete Element Method Based on Water Cycle Algorithm
by Chunhui Ma, Zhiyue Gao, Jie Yang, Lin Cheng and Tianhao Zhao
Water 2022, 14(3), 439; https://doi.org/10.3390/w14030439 - 01 Feb 2022
Cited by 7 | Viewed by 1606
Abstract
The viscous boundary has a direct influence on the accuracy of structural dynamic response analysis, and the absorbing effect of the viscous boundary is controlled by the adjustment coefficient. Therefore, a calibration model of the viscous boundary’s adjustment coefficient based on the water [...] Read more.
The viscous boundary has a direct influence on the accuracy of structural dynamic response analysis, and the absorbing effect of the viscous boundary is controlled by the adjustment coefficient. Therefore, a calibration model of the viscous boundary’s adjustment coefficient based on the water cycle algorithm is established for the particle discrete element to improve the accuracy of dynamic response analysis. First, the traditional viscous boundary theory is utilized to realize the viscous boundary’s application method in the particle discrete element via programming. This avoids the reflection and superposition of seismic waves at the boundary and makes the structural dynamic response with the particle discrete element more real and accurate. Second, for the complex and time-consuming adjustment coefficients determination, a calibration model based on the water cycle algorithm and Latin hypercube sampling is established for the adjustment coefficients in the particle discrete element method. Finally, this calibration model is employed for the seismic response analysis of a rockfill slope, the maximum velocity of rock in this rockfill slope being about 1.30 times that of a seismic wave. Comparing the rockfill slope response with fixed and viscous boundaries, the calibration’s accuracy and the viscous boundary’s feasibility are demonstrated, further expanding the research and application of the particle discrete element method in dynamic response analysis. Full article
(This article belongs to the Special Issue Granular Flows Modeling and Simulation)
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16 pages, 7431 KiB  
Article
Simulating the Hydraulic Heave Phenomenon with Multiphase Fluid Flows Using CFD-DEM
by Qiong Xiao
Water 2020, 12(4), 1077; https://doi.org/10.3390/w12041077 - 09 Apr 2020
Cited by 3 | Viewed by 2389
Abstract
In geotechnical engineering, the seepage phenomena, especially regarding the hydraulic heave, is one of the most dangerous failure mechanisms related to infrastructural stability. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In this study, [...] Read more.
In geotechnical engineering, the seepage phenomena, especially regarding the hydraulic heave, is one of the most dangerous failure mechanisms related to infrastructural stability. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In this study, a computational fluid dynamics (CFD) solver was developed and coupled with discrete element method (DEM) software to simulate the seepage failure process for the three phases of soil, water, and air. Specimens were constructed with two layers of gap-graded particles to give different permeability properties in the vertical direction. More significant heave failure was observed for the sample with higher permeability in the upper layer. Special attention was drawn to the particle-scale observations of the internal structure and drag force to study the erosion mechanism. The soil filled with air bubbles produced a higher drag force in the region below the retaining wall and showed a larger loss of fine particles than the saturated soil, particularly in the initial stages. The results indicate that the impact of air bubbles would accelerate the development of the heave or boiling phenomenon and influence the stability of the system at an early stage. Full article
(This article belongs to the Special Issue Granular Flows Modeling and Simulation)
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15 pages, 10030 KiB  
Article
CFD–DEM Simulations of Seepage-Induced Erosion
by Qiong Xiao and Ji-Peng Wang
Water 2020, 12(3), 678; https://doi.org/10.3390/w12030678 - 02 Mar 2020
Cited by 15 | Viewed by 5033
Abstract
Increases in seepage force reduce the effective stress of particles and result in the erosion of particles, producing heave failure and piping. Sheet piles/cutoff walls are often employed in dams to control the seepage. In this study, a computational fluid dynamics solver involving [...] Read more.
Increases in seepage force reduce the effective stress of particles and result in the erosion of particles, producing heave failure and piping. Sheet piles/cutoff walls are often employed in dams to control the seepage. In this study, a computational fluid dynamics solver involving two fluid phases was developed and coupled with discrete element method software to simulate the piping process around a sheet pile/cutoff wall. Binary-sized particles were selected to study the impact of fine particles on the mechanisms of seepage. The seepage phenomenon mainly appeared among fine particles located in the downstream side, with the peak magnitudes of drag force and displacement occurring around the retaining wall. Based on the particle-scale observations, the impact of seepage produced a looser condition for the region concentrated around the retaining wall and resulted in an anisotropic condition in the soil skeleton. The results indicate that heave behavior occurs when the drag force located adjacent to the boundary on the downstream side is larger than the corresponding weight of the bulk soil. Full article
(This article belongs to the Special Issue Granular Flows Modeling and Simulation)
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