Abstract

In this talk, I will explore granular segregation which plays a critical role in avalanche dynamics and dune building. Segregation is the separation of grains with different properties—such as density or size—due to a variety of physical processes. Segregation not only occurs within avalanches in nature, but can also be observed in the kitchen in a cereal box where large particle rise to the top. This natural separation creates pattern formation at the grain scale which influence large-scale phenomena dramatically.

I will illustrate my research with data from a variety of laboratory experiments and two recent desert field campaigns in Qatar. I will also highlight some very recent laboratory work in which we investigate granular segregation using photoelasticity for the first time. My presentation includes three central messages: (1) we are able to reproduce and investigate key physical characteristics of avalanches in the laboratory, (2) the particle segregation results in strong layering in avalanches and (3) the internal structure of desert dunes features remarkable patterns and segregation, which we can visualize in unprecedented detail with geophysical techniques.