A granular material is a conglomeration of discrete solid Solid is one of the major states of matter. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other,, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction Friction is not a fundamental force, as it is derived from electromagnetic force between charged particles, including electrons, protons, atoms, and molecules, and so cannot be calculated from first principles, but instead must be found empirically. When contacting surfaces move relative to each other, the friction between the two surfaces when grains collide). The constituents that compose granular material must be large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 µm A micrometre or micron is one millionth of a metre, or equivalently one thousandth of a millimetre or one thousand nanometres. It can also be written in scientific notation as 1×10−6 m, meaning 1⁄1000000 m. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are icebergs An iceberg is a large piece of ice from freshwater that has broken off from a snow-formed glacier or ice shelf and is floating in open water. It may subsequently become frozen into pack ice. Alternatively, it may come to rest on the seabed in shallower water, causing ice scour or becoming an ice island and to asteroid belts The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt region is also termed the main belt to distinguish it from other concentrations of minor planets within the Solar System, of the solar system The Solar System[a] consists of the Sun and those celestial objects bound to it by gravity, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. Of the retinue of objects that orbit the Sun, most of the mass is contained within eight relatively solitary planets whose orbits are almost circular and with individual grains being asteroids Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are smaller than planets but larger than meteoroids. The term "asteroid" has historically been applied primarily to minor planets of the inner Solar System, as the outer Solar System.
Some examples of granular materials are nuts Nut is a hard shelled fruit of some plants that has an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts. Nuts are an important source of nutrients for both humans and wildlife, coal Coal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. It is composed primarily of carbon along with variable, sand Sand is a naturally occurring granular material composed of finely divided rock and mineral particles, rice Rice is the seed of a monocot plant Oryza sativa. As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East, South, Southeast Asia, the Middle East, Latin America, and the West Indies. It is the grain with the second highest worldwide production, after maize, coffee Coffee is a brewed drink prepared from roasted seeds, commonly called coffee beans, of the coffee plant. They are seeds of coffee cherries that grow on trees in over 70 countries. Green coffee is one of the most traded agricultural commodities in the world. Due to its caffeine content, coffee can have a stimulating effect in humans. Today, coffee, corn flakes, fertilizer Fertilizers are soil amendments applied to promote plant growth; the main [[plant nutrition|nutrients present in fertilizer are nitrogen, phosphorus, and potassium and other nutrients ('micronutrients') are added in smaller amounts. Fertilizers are usually directly applied to soil, and also sprayed on leaves ('foliar feeding'), and ball bearings A ball bearing is a type of rolling-element bearing which uses balls to maintain the separation between the moving parts of the bearing. Powders A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have are a special class of granular material due to their small particle size, which makes them more cohesive Cohesion or cohesive attraction or cohesive force is a physical property of a substance, caused by the intermolecular attraction between like-molecules within a body or substance that acts to unite them and more easily suspended In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending agents. Unlike colloids, in a gas As a noun in the English language, a gas is one of three classical states of matter. Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized. Granular materials are commercially important in applications as diverse as pharmaceutical A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease industry, agriculture Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and stratified societies. The study of agriculture is known as, and energy production. Research into granular materials is thus directly applicable and goes back at least to Charles-Augustin de Coulomb Charles-Augustin de Coulomb was a French physicist. He is best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion. The SI unit of charge, the coulomb, was named after him, whose law of friction Friction is not a fundamental force, as it is derived from electromagnetic force between charged particles, including electrons, protons, atoms, and molecules, and so cannot be calculated from first principles, but instead must be found empirically. When contacting surfaces move relative to each other, the friction between the two surfaces was originally stated for granular materials.
According to material scientist Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It includes elements of applied Patrick Richard, "Granular materials are ubiquitous in nature Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic and are the second-most manipulated material in industry (the first one is water Water is a ubiquitous chemical substance that is composed of hydrogen and oxygen and is vital for all known forms of life)".
In some sense, granular materials do not constitute a single phase of matter In the physical sciences, a phase is a region of space , throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, and chemical composition. A simple description is that a phase is a region of material that is chemically uniform, physically distinct, and ( but have flow characteristics that roughly resemble those of ordinary Newtonian fluids A Newtonian fluid is a fluid whose stress versus strain rate curve is linear and passes through the origin. The constant of proportionality is known as the viscosity. However, granular materials dissipate energy quickly, so techniques of statistical mechanics Statistical mechanics is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. It provides a framework for relating the microscopic properties of individual atoms and molecules to that assume conservation of energy are of limited use. Depending on the average energy of the individual grains they may exhibit the properties of solids Solid is one of the major states of matter. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other,, liquids Liquid is one of the three classical states of matter. Like a gas, a liquid is able to flow and take the shape of a container, but, like a solid, it resists compression. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension,, or gases As a noun in the English language, a gas is one of three classical states of matter. Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized. When the average energy of the individual grains is low and the grains are fairly stationary relative to each other, the granular material acts like a solid. When the granular matter is driven and energy is fed into the system (such as by shaking) such that the grains are not in constant contact with each other, the granular material is said to fluidize and enter a liquid-like state. If the granular material is driven harder such that contacts between the grains become highly infrequent, the material enters a gaseous state. Correspondingly, one can define a granular temperature equal to the root mean square of grain velocity fluctuations that is analogous to thermodynamic temperature.
Bulk flow characteristics of granular materials do differ from those of homogeneous fluids In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, in several important ways:
- Shearing or shaking a granular material may result in its becoming inhomogeneous in space and time (see Brazil nut effect The Brazil nut effect is the name given to a phenomenon in which the largest particles end up on the surface when a granular material containing a mixture of objects of different sizes is shaken).
- Granular materials tend to clog when forced through a constriction (as in a salt cellar Salt is a dietary mineral composed primarily of sodium chloride that is essential for animal life, but can be toxic to many land plants. Salt flavor is one of the basic tastes, making salt the oldest, ubiquitous food seasoning. Salt is also an important preservative)
- A compacted granular material must expand (or dilate) before it can deform
- Turbulence In fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. Flow that is not turbulent is called laminar flow. While there is no theorem relating Reynolds is almost impossible to achieve in granular materials
- Granular materials can support (small) shear stresses indefinitely
- Granular materials are often inhomogeneous and anisotropic Isotropy is uniformity in all directions. Precise definitions depend on the subject area. The word is made up from Greek iso and tropos (direction). Exceptions, or inequalities, are frequently indicated by the prefix an, hence anisotropy. Anisotropy is also used to describe situations where properties vary systematically, dependent on direction
- Granular materials exhibit avalanches An avalanche is a rapid flow of snow down a slope, from either natural triggers or human activity. Typically occurring in mountainous terrain, an avalanche can mix air and water with the descending snow. Powerful avalanches have the capability to entrain ice, rocks, trees, and other material on the slope; however avalanches are always initiated in.
Granulation
Main article: Granulation (powder technology)Granulation is the act or process in which primary powder particles are made to adhere to form larger, multiparticle entities called granules.
References
- Duran, J., Sands, Powders, and Grains: An Introduction to the Physics of Granular Materials (translated by A. Reisinger). November 1999, Springer-Verlag New York, Inc., New York, ISBN 0-387-98656-1.
- Richard, P., Slow relaxation and compaction of granular systems. Nature Materials 4, 121–128 (2005) doi:10.1038/nmat1300
- Rodhes, M (editor),Principles of powder technology, John Wiley & Sons, 1997 ISBN 0-471-92422-9
- Fayed, M.E., Otten L. (editor), Handbook of powder science & technology, second edition, Chapman & Hall, ISBN 0-412-99621-9
- Fundamentals of Particle Technology - free book
- Pudasaini, Shiva P., Hutter, Kolumban, Avalanche Dynamics: Dynamics of Rapid Flows of Dense Granular Avalanches. Springer, Berlin, New York, 2007, ISBN 3-540-32686-3
- Lu, Kevin; et al. (November 2007). "Shear-weakening of the transitional regime for granular flow". J. Fluid Mech. 587: 347–372. doi A digital object identifier is a character string used to uniquely identify an electronic document or other entity. The DOI for a document remains fixed over the lifetime of the document, unlike URLs which can change when a publisher of online content changes its web server's file structure, and the DOI System provides a mechanism for locating an:10.1017/S0022112007007331. http://journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=1318128.
- Mester, L., The new physical-mechanical theory of granular materials. 2009, Homonnai, ISBN 96383-43-87
See also
- Fragile matter In materials science, fragile matter is a granular material that is jammed solid. Everyday examples include beans getting stuck in a hopper in a whole food shop, or milk powder getting jammed in an upside-down bottle. The term was coined by physicist Michael Cates, who asserts that such circumstances warrant a new class of materials. The jamming
- Liquefaction
- Particulate Particulates, alternatively referred to as particulate matter or fine particles, are tiny subdivisions of solid or liquid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural. Particulate Matter—(Water quality) In water pollution, particulates
- Paste (rheology) In physics, a paste is a substance that behaves as a solid until a sufficiently large load or stress is applied, at which point it flows like a fluid. In rheological terms, a paste is an example of a Bingham plastic fluid
- Sandcastle Sand art is the practice of modelling sand into an artistic form, such as a sand sculpture, sandpainting, or sand bottles. A sand castle is a type of sand sculpture resembling a miniature building, often a castle
Categories: Granular materials A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact . The constituents that compose granular material must be large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 | Discrete-phase flow
SYS-CON Media (press release)
If a single certificate, such as the developer certificate, is used for multiple applications, this granular revocation capability is lost. ...
admin
hu, 07 Jan 2010 08:20:32 GM
They allow flows of fluids and gases, . granular. -. material. flows, natural processes much as ornament manufacture on birdlike skins, mechanics of reserved gases, liberated boundaries, conductor devices, and socioeconomic processes. ...
Q. My science fair project is about coffee - can any of these proposals be tested without expensive equipment/extensive knowledge, and if so, how? I can't find a clear independent and dependent variable. The guidelines is that it is either a physics or chemistry project. It must either be an experiment or a prototype for a machine. 1. If the properties of density are used efficiently in the preparation of certain soft beverages and pairings thereof, their aesthetic, textural, and taste appeal could be heightened to grandiose levels. (i know, weird wording) 2. Could a robotic stirring mechanism do better (eg, be more accurate, more consistent) than a trained human? Or is there an irreplaceable component of motor control and feedback… [cont.]
Asked by alala - Fri Nov 27 14:12:09 2009 - - 1 Answers - 0 Comments
