Interdisciplinary Seminar in Nonlinear Science

Title: Vortices and clustering in anisotropic and cohesive granular matter
Speaker: Arshad Kudrolli
Speaker Info: Clark University
Brief Description:
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Granular matter have been the topic of a considerable number of inter-disciplinary investigations because of the fascinating properties exhibited by them and their importance in industrial and geophysical situations. However most of the studies have focused on non-cohesive granular matter. We will discuss a series of experiments where attractive forces are also present between particles. If a small amount of liquid is introduced in a granular mixture, capillary bridges introduce attractive forces. We will discuss the effect of the cohesivity on the angle of repose and segregation of granular matter. In a second series of experiments, we will discuss the effect of magnetizing the granular particles. The experimental system consists of magnetized steel beads that are supplied energy by vertical vibrations. For high amplitudes of vibration, a gas of beads is observed, but as the amplitude is lowered, the magnetized particles are observed to form clusters. We use high speed imaging to measure the positions to understand the structure of the clusters. Time permiting we will also discuss the observation of vortex patterns in granular rods vertically in a container. Above a critical packing fraction, moving domains of nearly vertical rods are spontaneously observed to form which coexist with horizontal rods.
Date: Friday, January 11, 2002
Time: 2:00PM
Where: Technological Institute - Room M416
Contact Person: Paul Umbanhowar
Contact email: umbanhowar@northwestern.edu
Contact Phone: 847-467-7291
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