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Toward an experimentally validated kinetic model of polydisperse bubble population dynamics

Simone Colucci1 , Antonio Buffo2, Federico Brogi1, Chiara Paola Montagna1

  • Affiliations: ^1 ^Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy; 2 Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, Torino, Italy

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 223

  • Programme No: 3.6.27

  • Theme 3 > Session 6

Abstract

A growing number of natural and experimental evidence shows that the variety of eruptive styles is intrinsically linked to micro-scale bubble dynamics. Nevertheless, the coupling of realistic micro-scale models for bubble dynamics and fluid dynamics of large-scale magma flow remains a challenge, due to the very different characteristic length and time scales. Moreover, while large-scale flow models are well-established and widely used, further advancements are needed to model bubble dynamics at the micro-scale. Most bubble dynamics models neglect the polydispersity (i.e., non-uniformity) of the bubble distribution and the experimental validation remains a critical aspect. Conventional "black-box" experiments used for validation provide a snapshot of the final state of the bubbly magma, at the end of the experimental run, but do not allow observing the temporal evolution of the bubble population. Here, we present a new kinetic model that describes the time evolution of a polydisperse population of gas bubbles in magma due to nucleation, growth and coalescence. The model is suited for incorporation into large-scale flow models. For validation, we re-analyzed literature data from "in situ" experimental observations of the time evolution of the distribution of the bubble population in a degassing magma. To analyze the experimental videos we developed a code for automatic image segmentation and rigorous statistical analysis. Preliminary results show that the model can capture the growth and coalescence of the bubble population and that "in situ" experiments represent a powerful approach for studying bubble dynamics and validating micro-scale models.