Transport and behavior of non-spherical particles in waves
Abstract/Contents
- Abstract
- Plastic pollution in the oceans is a global reality. Small dispersed plastic pieces impact ecosystems, fisheries, and water resources throughout the world. Most of this debris breaks down and persists as small particles, or microplastics. Accurately estimating microplastics accumulation rates and assessing ecosystem risk requires understanding the transport and fate of microplastics in the ocean. Of particular interest is how the characteristics of microplastic particles, such as their shape and size, affect their transport and how these effects interact with wavy flows inherent to the coasts and ocean surface. Regarding particle shape, the orientation of a non-spherical particle controls the lift and drag that it feels while moving through a fluid, which in turn affect transport. This thesis presents an analysis of the orientation of non-spherical particles in surface gravity waves, and the effects these findings have on transport. A theoretical study showed that spheroidal particles tend to a preferred orientation with a superimposed oscillation under waves. This behavior is a consequence of how the particle samples the flow and can be thought of as the angular analog of Stokes drift. The mean preferred orientation is found to be solely a function of the particle's shape; it is independent of the wave parameters. The implications of this theoretical result were explored with both numerical and laboratory experiments. Under both waves and shear flow, the theoretical limit for the preferential orientation was also derived. The effects of the waves and the particle characteristics are shown to be non-trivial for predicting dispersal of the particles. In particular, the vertical distribution of buoyant particles is found to be a strong function of particle settling velocity, a result with significant implications for microplastic transport models and in situ sampling. Results from this work show that accurately predicting the transport, settling velocity, vertical distribution and horizontal dispersion of anisotropic particles in wavy environments requires consideration of the shape and preferred orientation of the particles.
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 | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | DiBenedetto, Michelle Heather | |
|---|---|---|
| Degree supervisor | Ouellette, Nicholas (Nicholas Testroet), 1980- | |
| Thesis advisor | Ouellette, Nicholas (Nicholas Testroet), 1980- | |
| Thesis advisor | Dabiri, John O. (John Oluseun) | |
| Thesis advisor | Koseff, Jeffrey Russell | |
| Thesis advisor | Monismith, Stephen Gene | |
| Degree committee member | Dabiri, John O. (John Oluseun) | |
| Degree committee member | Koseff, Jeffrey Russell | |
| Degree committee member | Monismith, Stephen Gene | |
| Associated with | Stanford University, Civil & Environmental Engineering Department. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Michelle Heather DiBenedetto. |
|---|---|
| Note | Submitted to the Civil & Environmental Engineering Department. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Michelle Heather DiBenedetto
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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