Newland, EL;
Woods, AW;
(2024)
The dynamics of impinging plumes from a moving source.
Journal of Fluid Mechanics
, 982
, Article A6. 10.1017/jfm.2024.104.
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Abstract
We present the results from a series of experiments investigating the dynamics of gravity currents which form when a dense saline or particle-laden plume issuing from a moving source interacts with a horizontal surface. We define the dimensionless parameter P as the ratio of the source speed, ua, to the buoyancy speed, (B0/z0)1/3, where B0 and z0 are the source buoyancy flux and height above the horizontal surface, respectively. Using our experimental data, we determine that the limiting case in which P = Pc the gravity current only spreads downstream of the initial impact point occurs when Pc = 0.83 ± 0.02. For P < Pc, from our experiments we observe that the plume forms a gravity current that spreads out in all directions from the point of impact and the propagation of the gravity current is analogous to a classical constant-flux gravity current. For P > Pc, we observe that the descending plume is bent over and develops a pair of counter-rotating line vortices along the axis of the plume. The ensuing gravity current spreads out downstream of the source, normal to the motion of the source. Analogous processes occur with particle-laden plumes, but there is a second dimensionless parameter S, the ratio of the particle fall speed, vs, to the vertical speed of a plume in a crossflow, (B0/uaz0)1/2. For S 1, particles remain well mixed in the plume and a particle-driven gravity current develops. For S 1, particles separate from the plume prior to impacting the boundary which leads to a fall deposit and no gravity current. We discuss these results in the context of deep-sea mining.
| Type: | Article |
|---|---|
| Title: | The dynamics of impinging plumes from a moving source |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1017/jfm.2024.104 |
| Publisher version: | https://doi.org/10.1017/jfm.2024.104 |
| Language: | English |
| Additional information: | © The Author(s), 2024. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. |
| Keywords: | plumes/thermals, gravity currents, sediment transport |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10205039 |
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