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Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

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Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of Civil Engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China College of Civil and Transportation Engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method granular media

Effective thermal conductivity in granular media with devolatilization:the Lattice Boltzmann modelling

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International Journal of Coal Science & Technology 2021年第4期8卷 590-604页

作者： Arkadiusz Grucelski Institute of Fluid Flow Machinery Polish Academy of SciencesFiszera 1480-231GdanskPoland

Flow thermomechanics in reactive porous media is of importance in industry including the thermal processing of fossil fuel(coking understood as a slow pyrolysis)involving *** the way to provide a detailed description of the process,a multi-scale approach was chosen to estimate effective transport *** this case the Lattice Boltzmann method(LBM)was used due to its advantages to accurately model multi-physics and chemistry in a random geometry of granular *** account for earlier studies,the paper presents description of the model with improved boundary conditions and a benchmark *** from meso-scale LBM calculations are presented and discussed regarding the spatial resolution and the choice of relaxation parameter along its influence on the accuracy compared with empirical *** the estimation of effective thermal conductivity coefficient it is shown that occurrence of devolatilization has a crucial effect by reducing heat *** quantitative results characterise the propagation of thermal front;also presented is the evolution of effective thermal *** work is a step forward towards a physically sound simulation of thermal processing of fossil fuel.

关键词： Coking Effective heat transfer coefficient granular media Meso-scale modelling Lattice Boltzmann Method

Enhancing undulation of soft robots in granular media:A numerical and experimental study on the effect of anisotropic scales

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Biomimetic Intelligence & Robotics 2024年第2期4卷 63-70页

作者： Longchuan Li Chaoyue Zhao Shuqian He Qiukai Qi Shuai Kang Shugen Ma College of Information Science and Technology Bejing University of Chemical TechnologyBejing 100029China School of Engineering Mathematics and Technology University of BristolBristol BS81THUK College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China Thrust of Robotics and Autonomous Systems The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511453China

Generating efficient locomotion in granular media is important,although it is difficult for *** by the fact that sand vipers usually have saw-like scales,in this study,we design a soft undulation robot with tangential anisotropic friction to enhance the undulation performance of soft robots in granular media.A mathematical model was derived and numerical simulations were conducted accordingly to investigate the effectiveness of tangential friction anisotropy for undulation gait generation in granular *** particular,we introduce a pseudo-rigid-body dynamics model consisting of links and joints while simulating the pneumatic actuation method to more closely approximate the response of soft ***,a soft snake-like robot was fabricated,and its forward and reverse undulations were compared in two sets of controlled *** consistency between the experimental results and the numerical simulations confirms that tangential anisotropic friction induces a propulsive effect in undulation,thereby increasing the robot's locomotion *** discovery provides new insights into the design of undulation robots in granular environments.2024 The Author(s).Published by Elsevier *** behalf of Shandong *** is an open access articleunder the CCBY license(http://***/licenses/by/4.0/).

关键词： granular media Anisotropicity Pseudo-rigid-body model Soft robot Undulation

Numerical modeling of fluid-particle interaction in granular media

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Theoretical & Applied Mechanics Letters 2013年第2期3卷 37-40页

作者： Jidong Zhao Tong Shan Department of Civil and Environmental Engineering Hong Kong University of Science and Technology

Fluid-particle interaction underpins important behavior of granular media. Particle-scale simulation may help to provide key microscopic information governing the interaction and offer better understanding of granular media as a whole. This paper presents a coupled computational fluid dynamics and discrete element method （CFD-DEM） approach for this purpose. The granular particle system is modeled by DEM, while the fluid flow is simulated by solving the locally averaged Navier-Stokes equation with CFD. The coupling is considered by exchanging such interaction forces as drag force and buoyancy force between the DEM and CFD. The approach is benchmarked by two classic geomechanics problems for which analytical solutions are available, and is further applied to the prediction of sand heap formation in water through hopper flow. It is demonstrated that the key characteristic of granular materials interacting with pore water can be successfully captured by the proposed method.

关键词： granular media fluid-particle interaction coupled CFD-DEM single particle settling 1Dconsolidation sand pile pressure dip

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An inverse analysis of fluid flow through granular media using differentiable lattice Boltzmann method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2077-2090页

作者： Qiuyu Wang Krishna Kumar Department of Civil Architectural and Environmental EngineeringUniversity of Texas at AustinAustin78712-2100USA

This study presents a method for the inverse analysis of fluid flow *** focus is put on accurately determining boundary conditions and characterizing the physical properties of granular media,such as permeability,and fluid components,like *** primary aim is to deduce either constant pressure head or pressure profiles,given the known velocity field at a steady-state flow through a conduit containing obstacles,including walls,spheres,and *** lattice Boltzmann method(LBM)combined with automatic differentiation(AD)(AD-LBM)is employed,with the help of the GPU-capable Taichi programming language.A lightweight tape is used to generate gradients for the entire LBM simulation,enabling end-to-end *** AD-LBM approach accurately estimates the boundary conditions for complex flow paths in porous media,leading to observed steady-state velocity fields and deriving macro-scale permeability and fluid *** method demonstrates significant advantages in terms of prediction accuracy and computational efficiency,making it a powerful tool for solving inverse fluid flow problems in various applications.

关键词： Inverse problem Fluid flow granular media Automatic differentiation(AD) Lattice Boltzmann method(LBM)

Sound propagation and inversion of parameters in concentrated granular media

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Progress in Natural Science:Materials International 1995年第2期 3-12页

作者：钱祖文 Beijing 100080 China Chinese Academy of Sciences State Key Laboratory of Acoustics Insutate of Acoustics

If a complex medium consists of a matrix one and a (or several) inclusion(s), we call it the granular medium. In shallow sediments in ocean, for example, the matrix and the inclusion are seawater the sand graim, respectively Furthermore, bubbly water, petroleum and natural gas in the earth can be referred to as the granular media too

关键词： granular media sediments bubbly curtain inversion-

Discrete Modeling of Fluid-Particle Interaction in granular media

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Discrete Modeling of Fluid-Particle Interaction in Granular ...

Lattice Boltzmann simulation of fluid flow through random packing beds of Platonic particles: Effect of particle characteristics

2012颗粒材料计算力学会议

作者： Zhao Ji-Dong Shan TongHong Kong University of Science and Technology,Clear Water Bay,Hong Kong

This paper presents a coupled Computational Fluid Dynamics(CFD) and Discrete Element Method(DEM)approach to model the interaction between fluid and granular particles and its impact to relevant *** force and buoyancy force are considered to be the interaction forces exchanged between consecutiveDEM simulations and CFD *** numerical tool is verified by benchmarking simulations of thesettlement of single particle into water and the classic one-dimensional consolidation *** both cases goodagreements are found between the numerical predictions and the analytical *** have further applied thenumerical tool to the simulation of sand pile formed in water and debris flow into water *** varioussimulations demonstrate that the influence of fluid-particle interaction is well captured by the proposed method.

关键词： granular media fluid-particle interaction coupled CFD-DEM granular flow

来源： cnki会议评论

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Particuology 2019年第6期17卷 41-53页

作者： Jianjun Lin Huisu Chen Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China

The influence of particle characteristics,such as shape,size,and volume fraction,on the permeability of porous media was investigated by combining the randomly packed beds of Platonic particles with the lattice Boltzmann *** solutions of the permeability as a function of these characteristic parameters in mono-sized particle packing structures were *** D3Q19 model is presented here,which was tested by three simple benchmark tests.A series of packed beds of Platonic particles as well as spherical particles were generated in a random *** studies on factors influencing the permeability of materials were carried out to comprehensively study their *** results revealed that the permeability significantly increased with increasing equivalent diameter of the particles(or decreasing volume fraction).At a fixed size and volume fraction of particles,the permeability of the Platonic particle packing structures was also influenced by particle morphology:permeability significantly reduced as the particle sphericity *** permeability of tetrahedral particle packing structures dropped by more than 40%compared with that of corresponding spherical particle systems.

关键词： Platonic particles Lattice Boltzmann method granular media Fluid flow Particle characteristics

Modeling slow deformation of polygonal particles using DEM

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Particuology 2008年第6期6卷 506-514页

作者： Andrés A. Pea Pedro G. Lind Hans J. Herrmann Institute for Computational Physics Universitt Stuttgart Computational Physics IfB HIF E12 ETH Hnggerberg CH-8093 Zrich Switzerland Departamento de Física Universidade Federal do Ceará

We introduce two improvements in the numerical scheme to simulate collision and slow shearing of irregular particles. First, we propose an alternative approach based on simple relations to compute the frictional contact forces. The approach improves efficiency and accuracy of the Discrete Element Method （DEM） when modeling the dynamics of the granular packing. We determine the proper upper limit for the integration step in the standard numerical scheme using a wide range of material parameters. To this end, we study the kinetic energy decay in a stress controlled test between two particles. Second, we show that the usual way of defining the contact plane between two polygonal particles is, in general, not unique which leads to discontinuities in the direction of the contact plane while particles move. To solve this drawback, we introduce an accurate definition for the contact plane based on the shape of the overlap area between touching particles, which evolves continuously in time.

关键词： granular media Discrete element method Slow deformation Contact forces

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