Collaborative Research: Measurement of Particle Aggregation in Laboratory-scale Flows for Improved Models of Volcanic Ash Fallout and Entrainment

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Volcanic eruptions produce clouds of ash, which are hazardous to air travel and infrastructure. In emergencies, forecasters predict the transport of ash using numerical models, but they typically assume that particles fall as individuals to simplify the analysis. In reality, fine ash particles combine together into larger clusters, accelerating their rate of fall. This allows the ash to fall out of the cloud. Rates of aggregation depend on many factors, including moisture, electric charge, and turbulence. There is limited existing data on the effects of these properties, particularly for turbulent flows, even though aggregation affects up to 95% of fallout in some eruptions. Hence, there is a need for better experimental measurements of aggregation processes, along with more advanced models that include the phenomenon.This study aims to improve forecasting of volcanic hazards through both high-accuracy experiments and upgraded models. Ash aggregation will be examined in two different, relevant flow conditions: homogeneous turbulence and high-speed jets. High-resolution optical techniques will be used to study the flow, turbulence, and particle clustering. The results will be integrated into state-of-the-art analytical models, including some used for forecasting. Further, this research will be presented to the broader public through a series of hands-on demonstrations at the Oregon Museum of Science and Industry (OMSI).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.