Inside the Behavior of Granular Materials

Granular materials - like sand, rice, or powdered pharmaceuticals - are everywhere, yet their behavior is poorly understood. In some ways behaving like liquids, in other ways behaving like solids, such materials have unique properties and pose unique questions to answer. From clogged coal hoppers to powdered-snow avalanches, scientists and engineers are gaining new perspective on the fundamental nature of grains. In this video, see some of the latest research into the behavior of granular materials.

Transcript

00:00:07 [Music] granular materials are made up of many small solid particles yet flow like a liquid or freeze like a block of ice a collection of grains all acting together create new characteristics as if they are not individual bits and pieces but entirely new material remember the rice many granular materials function in

00:00:37 similar ways so understanding the same properties that dictate the flow of Parmesan on Pizza may help us guide the flow of coal in a hopper or even understand the powdered snow that can prime Avalanches powdered snow is like is a granular material actually most of the time when it's on a hillside um wet snow on top of it will keep it from keep it in

00:01:01 place and under the right conditions like you get a loud noise or loud resonant noise or something like that uh the powder snow begins to become act like a fluid and the snow you get an ambil scientists and Engineers hope to learn not only how granular material systems work but if they can be used as models for processes like the flowing or freezing of water molecules that occur

00:01:29 at the scale of Nan meters billions of a meter there's a fundamental aspect of this where you learn something about the way states of matter transform from one state to another and whether in fact it's deeper whether what works for atoms and molecules actually works for grains and bigger things as well if we are going to understand the mystery of granular materials we must watch how the

00:01:52 grains sift how they mix and figure out why those pesky grains are so prone to jamming one key appears to be how the grains strike each other when force is applied to them the bolts of strain seen here called Force chains reflect bands of stress that carry a push of force from the point of contact with the outermost grains inwards from grain to grain until the force dissipates Force

00:02:18 chains are just special lines of particles in a grinding material it's where much of the force is carried in a grind sample and it's in fact because there's so much of the force carried on the force chains that it's really important to study them if scientists and Engineers can figure out exactly how and why such forces travel through beds of grains they can gain true insight

00:02:39 into fundamental physical processes with far-reaching impacts so what one expects in things particularly like Avalanches or even earthquakes where you have a lot of Shear in the system those should be dominated by force chains so that when you understand the way Force chains be behave in a well-rolled lab system there are immediate applications to all sorts of of flowing systems Avalanches flows

00:03:02 and Hoppers earthquakes Etc if you understand the conditions under which something can transform from being um a jammed solid like thing that doesn't move to one that flows freely then you can control industrial processes and so forth once scientists cracked the granular code it could lead to direct impacts on the energy pharmaceutical and agricultural Industries help us better

00:03:29 prepare for natural disasters and perhaps even reveal the most fundamental nature of how liquids freeze [Music]