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AEM Seminar: The Fluid Dynamics of Explosive Volcanic Eruptions: Multiscale Flow in Eruptive Plumes and Pyroclastic Density Currents

Dr. Josef Dufek, Professor and Associate Chair, School of Earth and Atmospheric Sciences, Georgia Institute of Technology

2:30 PM on 2018-05-04

Akerman 319


Abstract:

Explosive volcanic eruptions produce flows that span a range of fluid dynamic regimes, and the ability of these flows to transform from one regime to another plays a significant role in their ability to modify the crust, landscape and atmosphere and produce hazardous conditions. A growing body of numerical, experimental and observational evidence indicates that homogeneity in particle-fluid systems is the exception rather than the rule. Particle segregation is not a passive process, and can feedback in the rheology of granular mixtures controlling the mixing and run-out distance of particle-laden flows. The aim of this talk is to discuss progress in using fluid and granular mechanics to understand the multiphase transport physics of volcanic flows, and demonstrate how an understanding of the dynamics of these high-energy, end member flows yields insight into a range of other geophysical flow types.

I will discuss the use of multiphase models in addressing the different scales of fluid motion in volcanic multiphase flow as well as how they can provide a platform to integrate microphysical, analogue experiments and observational constraints. Microphysical experiments can provide the necessary closure for statistical mechanics based models, and provide a way to examine grain-scale processes in a probabilistic manner. Such small-scale processes can dramatically alter the flow dynamics. One of the primary goals and utilities of this combined approach is that it enables comparison with diverse datasets, integrating previously disparate observations. In this talk I will illustrate eruptive flow styles that cover very different dynamic ranges and observation types, and in particular discuss the fluid dynamics of near vent entrainment and pyroclastic density currents.

In each case, laboratory experiments, numerical modeling results and observations will be combined to decipher physical processes. The insight from these approaches will also be discussed in the context of future terrestrial measurements as well as to give insight into planetary processes where conditions may have differed considerably from those on contemporary Earth.

Bio:

Josef Dufek studies physical processes in planetary interiors, volcanic eruption dynamics, and multiphase flows that shape the landscape. The Dufek lab is primarily focused on the application of fluid dynamics to understand mass and energy transfer in geological processes, with particular emphasis on volcanic systems. One of the Dufek lab’s research goals is to delineate how multiphase interactions contribute to the structure and composition of planetary interiors, and the role of such interactions in determining the dynamics and deposit architecture of volcanic flows using computational, experimental and field studies.

Josef Dufek received a B.S. in Geophysical Sciences from the University of Chicago and a Ph.D. in Earth and Space Science from the University of Washington. He was a Miller Postdoctoral Fellow at the University of California, Berkeley, and joined the faculty in the School of Earth and Atmospheric Science at Georgia Tech in 2008. He recently accepted a position as a faculty member at the University of Oregon He is a fellow of the American Geophysical Union, and is the Lillis Professor of Volcanology in the newly endowed Center for Volcanology at the University of Oregon.


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