Description:

Title: Crystallization in a periodically perturbed random granular medium

Speaker: Harry Swinney, Professor Emeritus, Physics Department and the Center for Nonlinear Dynamics, University of Texas at Austin

Abstract: An understanding of crystal formation in a homogeneous disordered state can provide insights into crystallization in a fluid, such as the formation of ice crystals in water, which is still poorly understood. Experiments on packings of spheres over the past half century suggest that under repeated small disturbances, the spheres reach a “Random Close Packed” (RCP) state where the spheres occupy a maximum fraction of the container volume, 0.62-0.66. This talk will describe an experiment and numerical simulations on hard spheres that reveal that randomly packed spheres, after repeated small disturbances, occupy a well-defined volume fraction, 0.646±0.001. Further small disturbances lead to the nucleation of crystallites that, if they reach a critical size of 10-15 spheres, grow rapidly, and ultimately the container is filled with crystallites.   

Special note: This event will be held in person, and will be simultaneously broadcast on Zoom. The event can be accessed remotely at the following link:  https://northwestern.zoom.us/j/98251574799.

-----

To subscribe to the Applied Mathematics Colloquia List send a message to seminar-join@esam.northwestern.edu