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Granular Materials: Liquid-like Properties of Sand

By Krista Knappman Physics NSF REU 1999 Program The Ohio State University Advisors: Maarten Rutgers/David Andereck


Granular materials are made up of many small pieces that can move either

separately or together. Some examples of different granular materials are sand, soil,

grain, corn, plastic pellets, powders, and pills. These materials tend to have many

different physical properties. They appear both liquid- or solid-like. For example, a pile

of sand is more like a solid, while a vibrated or fluidized bed of sand can be more like a

liquid like quicksand. This is important in life and industry.

There are many different situations that demonstrate this behavior. One example

is an hourglass filled with sand. The sand can flow through the glass like a liquid, but at

the same time a mass, such as a person, can stand on top of the sand as if it were solid

(seen in figure 1). Another example is a sandcastle. With a sandcastle, the wet sand can

be held together like a solid, but it can also fall apart as it dries, flowing down resembling

an avalanche pattern. S. Nasuno, A. Kudrolli, et al.1 have further described this stick-slip

motion with sand. One of the main interests is the liquid-like property of sand during an

earthquake. In an earthquake, the vibrations, with the help of water-saturated ground, the

buildings to sink in the sand as shown in figure 2. P. Evesque2 explained this property in

his research. These vibrations make the sand act like a liquid. Though sand may appear

liquid-like, it is not yet known if any standard fluid dynamical principles can be applied.

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