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Granular materials affect a variety of industries -- from
pharmaceutical to metallurgical to ceramic -- and are quickly becoming
a topic of active research for chemical engineers. It is well known
that the properties of many materials are directly related to
understanding and manipulating granular processing variables. In fact,
it has been estimated that granular processing accounts for as much as
$61 Billion, 40% of the value added by the chemical industry. Some
industrial examples of powder technology include: mixing and tableting
of pharmaceutical powders, morphological control via changes in
microstructure in powder metallurgy, and heat transfer in particulate
ceramics production.
Possibly the biggest hindrance to an understanding of
powder processing is that there is no accepted set of fundamental
equations governing the flow of a granular material. This lack of a
universal mathematical description can be attributed to the intrinsic
physical complexity of the rheology and also, in part, to the
difficulty in experimentally measuring the bulk properties of the
materials. Despite this difficulty, three viewpoints used by our group
provide an efficient and useful method of analysis for many problems of
powder processing: a geometrical approach, a kinematic approach, and a
micro-mechanical approach.
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