A mechanism for the increased wave-induced drift of floating marine litter
| Autor: | Colin Whittaker, T. S. van den Bremer, R. Calvert, Alistair G.L. Borthwick, M. L. McAllister, Alison Raby |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Buoyancy
010504 meteorology & atmospheric sciences engineering.material 01 natural sciences Physics::Geophysics 010305 fluids & plasmas symbols.namesake Geophysical and Geological Flows surface gravity waves Surface gravity waves 0103 physical sciences Marine debris Perpendicular coastal engineering ocean processes Physics::Atmospheric and Oceanic Physics 0105 earth and related environmental sciences Stokes drift Physics Mechanical Engineering Mechanics Ocean processes Condensed Matter Physics Coastal engineering Mechanism (engineering) Mechanics of Materials Waves/Free-surface Flows symbols engineering Lagrangian |
| Zdroj: | Journal of Fluid Mechanics, 915 Calvert, R, McAllister, M L, Whittaker, C, Raby, A, Borthwick, A & Van Den Bremer, T 2021, ' A mechanism for the increased wave-induced drift of floating marine litter ', Journal of Fluid Mechanics, vol. 915, A73 . https://doi.org/10.1017/jfm.2021.72 |
| ISSN: | 0022-1120 |
| DOI: | 10.1017/jfm.2021.72 |
| Popis: | Periodic water waves generate Stokes drift as manifest from the orbits of Lagrangian particles not fully closing. Stokes drift can contribute to the transport of floating marine litter, including plastic. Previously, marine litter objects have been considered to be perfect Lagrangian tracers, travelling with the Stokes drift of the waves. However, floating marine litter objects have large ranges of sizes and densities, which potentially result in different rates of transport by waves due to the non-Lagrangian behaviour of the objects. Through a combination of theory and experiments for idealised spherical objects in deep-water waves, we show that different objects are transported at different rates depending on their size and density, and that larger buoyant objects can have increased drift compared with Lagrangian tracers. We show that the mechanism for the increased drift observed in our experiments comprises the variable submergence and the corresponding dynamic buoyancy force components in a direction perpendicular to the local water surface. This leads to an amplification of the drift of these objects compared to the Stokes drift when averaged over the wave cycle. Using an expansion in wave steepness, we derive a closed-form approximation for this increased drift, which can be included in ocean-scale models of marine litter transport. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|