Wetgranularmaterials资源-CSDN文库

版权申诉

文档资料

EDEM

67 浏览量 2022-05-31 22:41:03 上传评论收藏 843KB PDF 举报

资源详情

资源评论

Advances in Physics,

Vol. 55, Nos. 1–2, January–April 2006, 1–45

Wet granular materials

NAMIKO MITARAI*y and FRANCO NORIz}

yDepartment of Physics, Kyushu University 33, Fukuoka 812-8581, Japan

zFrontier Research System, The Institute of Physical and Chemical Research

(RIKEN), Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan

}Center for Theoretical Physics, Physics Department, Center for the Study

of Complex Systems, The University of Michigan, Ann Arbor,

Michigan 48109-1040, USA

(Received 26 July 2005; in ﬁnal form 2 September 2005)

Most studies on granular physics have focused on dry granular media, with no

liquids between the grains. However, in geology and many real world applications

(e.g. food processing, pharmaceuticals, ceramics, civil engineering, construction,

and many industrial applications), liquid is present between the grains. This

produces inter-grain cohesion and drastically modiﬁes the mechanical

properties of the granular media (e.g. the surface angle can be larger than 90

degrees). Here we present a review of the mechanical properties of wet granular

media, with particular emphasis on the eﬀect of cohesion. We also list several

open problems that might motivate future studies in this exciting but mostly

unexplored ﬁeld.

Keywords: Granular material; Wet grains; Cohesion

Contents pag e

1. Introduction 2

1.1. Granular physics and wet granular media 2

1.2. What is different from dry granular media? 3

2. Wet granular media: Grains with liquid and air 5

2.1. Cohesion between two spheres 5

2.1.1. Meniscus and suction 5

2.1.2. Liquid bridge between two spheres 6

2.2. Wet granular media with various liquid content 7

2.2.1. Four states of liquid content: pendular, funicular, capillary, and

slurry state 7

2.2.2. Liquid content and suction 8

2.2.2.1. Measurement of suction in granular media 8

2.2.2.2. Relation between the liquid content and suction 10

3. Mechanical properties 12

3.1. Granular cohesion in the static and quasi-static regimes 12

3.1.1. Compaction of wet granular media 12

3.1.2. Angle of repose for small amounts of liquid 13

*Corresponding author. Email: namiko@stat.phys.kyushu-u.ac.jp

Advances in Physics

ISSN 0001–8732 print/ISSN 1460–6976 online # 2006 Taylor & Francis

http://www.tandf.co.uk/journals

DOI: 10.1080/00018730600626065

3.1.2.1. Experiments 13

3.1.2.2. Cohesion and angle of repose 14

3.1.3. Tensile, compression, and shear tests for intermediate

and large liquid content 19

3.1.3.1. Test methods and Mohr circle 19

3.1.3.2. Tests in the pendular state 23

3.1.3.3. Tests with intermediate liquid content 24

3.1.3.4. Tests in soil mechanics: relatively large amounts of liquid 25

3.2. Dynamical behaviour 27

3.2.1. Dynamics in the pendular state 28

3.2.1.1. Avalanches in rotating drums 28

3.2.1.2. Vibrated wet granular media 29

3.2.1.3. Segregation 31

3.2.2. Shear experiments for various liquid content 32

3.2.3. Dynamics of wet granular media: practical applications 35

3.2.3.1. Agglomeration processing: grains bound by liquid 35

3.2.3.2. Geological events 35

4. Summary and open questions 35

4.1. Effect of the liquid content on quasi-static behaviour 35

4.2. Open problems 36

4.2.1. Jamming 37

4.2.2. Statistical mechanics approach 39

4.2.3. Arches and contact-force fluctuations 39

4.2.4. Simple experimental set-ups to study the dynamics of wet granular media 39

4.2.5. Numerical simulations 40

4.2.6. Mechanical properties of snow 40

5. Conclusion 41

Acknowledgements 41

References 41

1. Introduction

1.1. Granular physics and wet granular media

Granular materials are collections of macroscopic particles, like glass beads or sand,

which are visible to the naked eye. Because of the macroscopic size of the particles,

thermal noise plays no role in particle motion, and particle–particle interactions are

dissipative. Therefore, continuous energy input by external forces (gravity,

vibrations, etc.) are necessary in order to keep them in motion. Particles may stay

at rest like a solid, ﬂow like a liquid, or behave like a gas, depending on the rate

of energy input. However, the external force is often not enough for the particles

to explore their phase space, which makes them quite diﬀerent from conventional

molecular systems.

The scientiﬁc study of granular media has a long history, mainly in the

engineering ﬁeld, and many physicists have joined the granular research community

over the past few decades (for reviews and books, see, e.g. [1–12]). Most studies

on granular media, especially in the physics ﬁeld, have focused on dry granular

materials, where the eﬀects of interstitial ﬂuids are negligible for the particle

dynamics. For dry granular media, the dominant interactions are inelastic collisions

2 N. Mitarai and F. Nori

and friction, which are short-range and non-cohesive. Even in this idealized situation,

dry granular media show unique and striking behaviour, which have attracted the

attention of many scientists for centuries.

In the real world, however, we often see wet granular materials, such as beach

sand. Dry and wet granular materials have many aspects in common, but there is one

big diﬀerence: Wet granular materials are cohesive due to surface tension.

In the past, many research groups that studied granular physics have been

struggling to minimize humidity and avoid inter-granular cohesive forces (e.g. [13]).

Indeed, some experiments were performed in vacuum chambers. Humidity and ﬂuids

in general were seen as a nuisance to be avoided at all costs. However, many important

real life applications involve mechanical properties of wet granular media.

Examples include rain-induced landslides, pharmaceuticals, food processing, mining

and construction industries. Thus, it is important to study the mechanical response

of granular matter with various degrees of wetness or liquid content.

In this review, we show how the cohesion induced by the liquid changes

the mechanical properties of granular materials. We mainly consider static or

quasi-static situations, where the cohesion dominates over other eﬀects of the

liquid, such as lubrication and viscosity. Some phenomena in this ﬁeld which are

not well-understood are presented below as ‘open problems’. Most references listed

at the end focus on experimental results. Theoretical approaches can be found in

the reviews cited below and references therein.

1.2. What is diﬀerent from dry granular media?

Studies of wet granular media have been made in many industrial applications. The

mechanical properties of wet granular media are also extremely important in geology

and civil engineering. For example, let us consider a huge and expensive civil works

project, the construction of the Kansai International Airport, on a man-made island

near Osaka. The weight of the 180 million cubic metres of landﬁll and facilities

compressed the seabed, composed of clay, inevitably causing the airport to sink by

some amount. The airport had sunk by 11.7 metres on average at the end of 2000,

and the settlement is still carefully monitored [14]. This with other examples from

geology and civil engineering stress the need to better understand the mechanical

properties of wet granular assemblies, both small and large.

The biggest eﬀect that the liquid in granular media induces is the cohesion

between grains. Even humidity in the air may result in a tiny liquid bridge at

a contact point, which introduces cohesion. The cohesion occurs in wet granular

material unless the system becomes overwet, i.e. the granular medium is completely

immersed in a liquid. In this short review, we focus on the eﬀect of this cohesion; the

system that we are considering is partially wet granular material, which is a mixture

of solid grains, liquid, and air.

In addition to cohesion, there are many eﬀects induced by the presence of

the liquid. One of them is the lubrication of solid–solid friction [15–17]. In addition,

the liquid viscosity may induce velocity-dependent behaviour and additional dissipa-

tion. These eﬀects are often seen in underwater experiments (e.g. [18, 19]). The

time-scale of liquid motion (how the liquid moves or ﬂows through granular

media) also aﬀects the dynamics. All of these eﬀects, of course, play important

Wet granular materials 3

roles in the properties of wet granular media. However, these are more or less

velocity-dependent phenomena; in the static or quasi-static regime, the cohesion

often plays the most important role, providing a signiﬁcant qualitative diﬀerence

from dry granular media.

The simplest situation where we see the eﬀect of cohesion in wet granular media

would be the sandpiles that children make in a sandbox. Let us ﬁrst consider a

sandpile made of dry grains, and afterwards wet grains.

When we make a sandpile using dry sand (ﬁgure 1(a)), the surface of the pile is

smooth, making a ﬁnite, well-deﬁned angle, which is about 35



. A slightly denser pile

might be made by tapping the surface, but would not change the shape of the pile by

much. Even if we try to make a sharper pile by pouring more dry sand, grains ﬂow

down along the pile surface, and the resulting angle is always around the same value.

It is easy to remove part of the sand from the pile, but we cannot make a tunnel

through a dry sandpile because the wall around the hole would collapse, and the

angle of the surface cannot be larger than the critical angle.

Let us add some water to the sand, and make another sandpile (ﬁgure 1(b)). We

can try to ﬁnd the optimal amount of water to produce a certain shape. Small

amounts of water do not allow the creation of many shapes, while too much

water results in muddy water that cannot keep a shape. With the proper amount

of water, we can make a sandpile with the surface angle larger than the dry case.

Indeed, the angle can be as large as 90



, or even larger, allowing the construction of

elaborate and stunning sandcastles (see, e.g. ﬁgure 2). This wet pile can be made

denser and stronger by tapping the surface. Now we can make a tunnel through

the pile, if we are suﬃciently careful. If we try to make a hole that is too large, the

pile would break down, forming some rugged surfaces.

Therefore, in a sandbox, we already learnt important properties of dry granular

media: a ﬁnite angle of repose, small hysteresis in packing, and small strength against

loading. We also learnt how drastically these properties are changed or enhanced by

adding a liquid, resulting in: a much larger angle of repose, stronger hysteresis in

packing, and enhanced strength against loading. These comparisons are summarized

in table 1. In the following sections, we will see how this behaviour is studied by

scientists.

Figure 1. (colour online). (a) Dry sandpile with a well-deﬁned surface angle. (b) Wet sandpile

with a tunnel.

4 N. Mitarai and F. Nori

剩余44页未读，继续阅读

评论收藏

内容反馈

版权申诉

Wet granular materials

评论0

最新资源

Wet granular materials

评论0

最新资源

相关推荐

Micro-deformation mechanism of granular materials under different boundary conditions based on DEM simulation

Numerical_modeling_of_immersed_granular_materials（已翻译为中文版）

handbook of granular computing

Granular

granular computing

Granular Computing Based Machine Learning A Big Data Processing 无水印原版pdf

2010_Discrete element modeling of direct shear tests for a granular material.pdf

granular_computing

Granular Computing Based Machine Learning: A Big Data Processing Approach

Granular Computing based Machine Learning. A Big Data Processing Approach

Model for collisions in granular gases.pdf

Handbook of Granular Computing

ExtremeLearningMachine资源共享-Granular-support-vector-machine-based-on-mixed-measure_2013_Neurocomputing.pdf

Modeling of heat transfer in granular flowin rotating vessels

A PACKING GENERATION SCHEME FOR THE GRANULAR.pdf

A granular extension of the fuzzy-ARTMAP (FAM)

PyPI 官网下载 | granular-moonshot-0.3.0.tar.gz

Python库 | django-granular-access-0.1.tar.gz

全国计算机等级考试二级Python真题及解析.docx

1000份ppt模版，PPT模板优秀PPT

matlab批量读取excel表格数据并处理画图

导入证书可以解决”无法建立到信任根颁发机构的证书链"问题。

OpenCv车辆识别训练模型

代码随想录知识星球精华-大厂面试八股文第二版v1.2.pdf

数学建模对乙醇偶合制备C4烯烃的问题研究

Vue-Element UI集成ECharts实现数据统计分析页代码部分(如果帮助到你，感谢关注点赞)

STM32F103C8T6中文数据手册

（头歌）计算机组成原理存储系统设计（HUST）1-7关答案

MATLAB深度学习入门实例（果树病虫害识别VGG19版）