CAREER: Static Properties and Dynamical Behavior of Jammed Systems

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This CAREER project will investigate connections between the microscopic and macroscopic properties of complex fluids. The systems studied are "jammed" materials, including colloidal suspensions, emulsions, and granular suspensions. All these materials possess similar microscopic properties, and recent theories propose that they share an underlying transition to the "jammed" state, analogous to a glass transition. The objective of this work is to utilize microscopy to provide crucial details for testing and extending theories of jamming. Experiments will connect the rheological behavior of these systems to the formation and dynamics of microscopic structures. The overarching goal is to clarify the mechanisms underlying jamming, which will be highly relevant to a large number of researchers studying granular materials, colloids, glass transitions, and nonlinear dynamics in complex fluids. Moreover, the insight from these experiments will be useful to the processing of industrially important materials. Undergraduate and graduate students involved will receive broad training in experimental techniques and computer data analysis. Because of the interdisciplinary nature of these systems as well as their relevance to technological and industrial processes, students involved in the project will be well trained for careers in academe, industry, or government. The project is co-supported with the Particulate and Multiphase Processes Program in the Division of Chemical and Transport Systems.This CAREER project will investigate connections between the small-scale structure of complex fluids and their large-scale flow behavior. The systems studied are "jammed" materials, including colloidal suspensions (small solid particles in a liquid), emulsions (liquid droplets in a second liquid), and granular particles (large solid particles). All these materials possess similar small-scale properties, and recent theories propose that they share an underlying transition to the "jammed" state analogous to how glasses become solid upon cooling. The objective of this proposal is to use microscopy to provide crucial details for testing and extending theories of jamming. Experiments connect the behavior of these materials as they flow through tubes or deform under applied forces, to the formation and motion of microscopic structures. The insight from these experiments will be useful to the processing of industrially important materials (such as food products, paints, pharmaceuticals, and oil). Undergraduate and graduate students involved receive broad training in experimental techniques and computer data analysis. Because of the interdisciplinary nature of these systems as well as their relevance to technological and industrial processes, students involved in the project will be well trained for careers in academe, industry, or government. The project is co-supported with the Particulate and Multiphase Processes Program in the Division of Chemical and Transport Systems.