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Disrupt the upper or the lower conduit? The dual role of gas exsolution in the conduits of persistently active volcanoes

Peng, Shirui and Picchi, Davide and Suckale, Jenny (2022) Disrupt the upper or the lower conduit? The dual role of gas exsolution in the conduits of persistently active volcanoes. Journal of Fluid Mechanics, 942 . Art. No. A24. ISSN 0022-1120. doi:10.1017/jfm.2022.346. https://resolver.caltech.edu/CaltechAUTHORS:20220722-769319000

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Abstract

Many volcanoes emit a significant portion of the gas they transport to the atmosphere during continual passive degassing rather than during eruptions. To maintain a high gas and thermal flux without erupting magma, the flow field in the volcanic conduit must be approximately balanced with gas-rich, buoyant magma ascending and degassed, heavy magma descending. In vertical conduits, this exchange flow takes the form of core–annular flow, where the gas-rich magma forms a core enclosed by an annulus of degassed magma. The flow dynamics of core–annular flow have been studied extensively in fluid dynamics, but mostly for constant material properties. Our study aims to advance our understanding of how core–annular flow responds to volatile exsolution – a simple, yet ubiquitous disruption in volcanic conduits, which alters both the density and the viscosity of the core fluid. By deriving an evolution equation for the core–annular interface based on a generalized exchange-flow condition using a lubrication approximation, we find that the response of the system to volatile exsolution depends on the conduit flow regime. The same nucleation event can lead to a flow adjustment only in the upper, only in the lower or in both portions of the volcanic conduit. Our results emphasize that the thermodynamic evolution of magma properties and volcanic conduit flow are intricately linked, which may help understand the observed variability of eruptive behaviour at persistently degassing volcanoes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1017/jfm.2022.346DOIArticle
https://static.cambridge.org/content/id/urn:cambridge.org:id:article:S0022112022003469/resource/name/S0022112022003469sup001.zipPublisherSupporting Information
http://zapad.stanford.edu/sigma/JFM2022_depthdependent_bidirectionalflowRelated ItemCode
ORCID:
AuthorORCID
Peng, Shirui0000-0002-4616-4604
Picchi, Davide0000-0002-2619-104X
Suckale, Jenny0000-0002-9787-8180
Additional Information:© The Author(s), 2022. Published by Cambridge University Press. (Received 20 August 2021; revised 25 March 2022; accepted 5 April 2022) Our work has benefited greatly from discussions with Z. Qin. We also acknowledge helpful conversations with K.V. Cashman, A. Rust, I. Battiato, A. Papula and P. Garaud. The manuscript was improved greatly through the thoughtful comments by two anonymous reviewers. This study was supported by NSF grant CH-2048430 awarded to J.S. The majority of research was performed using the facilities at Stanford University, where S.P. obtained his MS degree. Author contributions. S.P. derived the lubrication model, implemented it numerically, produced the figures presenting our simulations results and wrote the accompanying text. D.P. derived the analytical results, co-advised S.P. and contributed to the figure design and text. J.S. conceptualized the study, advised S.P., acquired funding and wrote some of the text. All authors have reviewed and approved the text. Open Research. The code used for our simulations of flow adjustment is available at http://zapad.stanford.edu/sigma/JFM2022_depthdependent_bidirectionalflow with open access. The usage instructions are provided in the README file of the repository. The authors report no conflict of interest.
Funders:
Funding AgencyGrant Number
NSFEAR-2048430
Subject Keywords:magma and lava flow, multiphase flow, lubrication theory
DOI:10.1017/jfm.2022.346
Record Number:CaltechAUTHORS:20220722-769319000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220722-769319000
Official Citation:Peng, S., Picchi, D., & Suckale, J. (2022). Disrupt the upper or the lower conduit? The dual role of gas exsolution in the conduits of persistently active volcanoes. Journal of Fluid Mechanics, 942, A24. doi:10.1017/jfm.2022.346
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115792
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:22 Jul 2022 23:08
Last Modified:22 Jul 2022 23:08

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