Research – Granular materials

During my PhD in the Department of Mathematics at MIT I studied the behavior of dense granular materials during flow. Despite being common in everyday experience, granular materials have a complex structure combining both solid-like and fluid-like properties, and there is no complete physical theory for how they behave.

Granular materials are of critical importance to many industrial processes where grains and powders must frequently be manipulated, and the lack of complex physical theory creates a serious problem in effectively designing industrial facilities. In my PhD, I studied the rheology of dense granular materials, and developed computational techniques for rapidly simulating granular flows with a particular focus on mixing. I wrote these short articles below to summarize the main findings. Much of this work was subsequently discussed in my publications and PhD thesis.


Simulations of the spot model

This describes the simulation of dense granular drainage using the spot model, summarizing the paper Dynamics of Random Packings in Granular Flow published in Physical Review E, 2006.


Stress, strain rate, and free volume

I made use of discrete-element simulation to probe the rheological properties of dense granular flow, with the aim of constructing a better continuum theory, or a general multiscale simulation technique.


Voronoi volumes and local density

I made use of Voronoi cells as a method of very accurately calculating free volume in a granular material on a local scale. This work formed the basis of the software library Voro++ that I subsequently wrote.


Granular flow in a pebble-bed reactor

I carried out discrete element simulations of a pebble-bed nuclear reactor design, in collaboration with Sandia National Laboratories, and described in Analysis of Granular Flow in a Pebble-Bed Nuclear Reactor, published in Physical Review E, 2006.