The role of turbulence in the aggregation of ash particles in volcanic plumes
Abstract/Contents
- Abstract
- Explosive volcanic eruptions eject large quantities of ash particles into the atmosphere. Fine ash can remain airborne for days following the eruption and travel for hundreds of kilometers before settling to the ground. Field observations indicate that much of the fine ash is stripped from the plume early on through the process of ash aggregation, which greatly reduces the residence time of ash in the atmosphere. Predicting the transport of ash requires better understanding of the aggregation process and is important for minimizing the societal impact of future eruptions. We present a new experimental apparatus, the turbulence tower, which replicates the conditions in the core of a water-rich buoyant plume at the lab-scale. The influence of turbulent mixing on aggregation of wetted particles is studied using a variety of optical techniques. In particular, high-speed imaging is used to detect individual collision events. The outcome of each collision is classified as either rebound, aggregation, or disaggregation, depending on the relative collision velocity and effective film thickness of water coating the particles. The experimental data are used to fit a semi-empirical sticking efficiency function. A 1D volcanic plume model that incorporates the effects of aggregation and turbulent mixing is also developed. The model is applied to the 2009 eruption of Redoubt Volcano, Alaska, predicting the plume rise height, concentration of hydrous phases, and ash aggregate grain size from a set of eruption source parameters.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Hoffman, Davis Wenham |
|---|---|
| Degree supervisor | Eaton, John K |
| Thesis advisor | Eaton, John K |
| Thesis advisor | Elkins, Christopher J |
| Thesis advisor | Ouellette, Nicholas (Nicholas Testroet), 1980- |
| Degree committee member | Elkins, Christopher J |
| Degree committee member | Ouellette, Nicholas (Nicholas Testroet), 1980- |
| Associated with | Stanford University, Department of Mechanical Engineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Davis W. Hoffman. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/dz177dw3065 |
Access conditions
- Copyright
- © 2021 by Davis Wenham Hoffman
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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