On simple models for gravity currents from moving sources

Ungarish, Marius

doi:10.1017/jfm.2022.924

Cited by 2 publications

(4 citation statements)

References 9 publications

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“…We can obtain a simple estimate of the distance the flow travels upstream by equating the speed of the source, to the speed of this upstream flow, By substituting (3.2) into (3.1), we find the relation for the upstream distance (cf. Ungarish 2022) and the time at which this condition is first satisfied In figure 3( c ), we plot the length, , (3.3) using the range of estimated from our experiments as a function of and find good agreement with out experimental data. After time we expect that the position of the front of the gravity current from the initial point of impact will be given by Our analysis of the shape of the gravity currents shows that the maximum length of the gravity current increases with time according to the relation (3.1).…”

Section: Single-phase Experimentssupporting

confidence: 56%

“…In this paper, we build on these earlier works, especially those of Ouillon et al (2021), Ungarish (2022) and James et al (2022), through an experimental study in which we systematically examine the dynamics of gravity currents that form when a dense single-phase or particle-laden plume, with buoyancy flux B 0 , issuing from a moving source at height z 0 above the sea bed, descends through the water column and then spreads out over the base of the experimental tank. First, we investigate the morphology of the gravity currents as a function of the source speed with a series of experiments on single-phase plumes.…”

Section: Introductionmentioning

confidence: 99%

“…However, as the source speed exceeds the gravity current speed the flow evolves downstream of the source, spreading laterally in a fashion similar to a two-dimensional (2-D) finite release gravity current (Hoult 1972). Ungarish (2022) presented a detailed comparison of the numerical results of Ouillon et al. (2021) with a box model formulation based on the classical theory of turbulent gravity currents.…”

Section: Introductionmentioning

confidence: 99%

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The dynamics of impinging plumes from a moving source

Newland,

Woods

2024

J. Fluid Mech.

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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, $u_a$ , to the buoyancy speed, $(B_0/z_0)^{1/3}$ , where $B_0$ and $z_0$ are the source buoyancy flux and height above the horizontal surface, respectively. Using our experimental data, we determine that the limiting case in which $P=P_c$ the gravity current only spreads downstream of the initial impact point occurs when $P_c=0.83\pm 0.02$ . For $P< P_c$ , 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 $P>P_c$ , 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, $v_s$ , to the vertical speed of a plume in a crossflow, $(B_0/u_a z_0)^{1/2}$ . For $S\ll 1$ , particles remain well mixed in the plume and a particle-driven gravity current develops. For $S\gg 1$ , 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.

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Section: Single-phase Experimentssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The dynamics of impinging plumes from a moving source

Newland,

Woods

2024

J. Fluid Mech.

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“…The flow that propagates upstream is arrested by the relative flow of the ambient environment, and reaches a maximum distance, x m . We can obtain a simple estimate of the distance the flow travels upstream by equating the speed of the source, w a to the speed of this upstream flow, equation 5.7, we find the relation for the upstream distance (cf Ungarish (2022)).…”

mentioning

confidence: 99%

Dynamics of deep-submarine explosive eruptions

Newland

Mingotti

Woods

2022

Preprint

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<div>Deposits from explosive submarine eruptions have been found in several deep-sea locations, with both flow and fall deposits of small clasts, 1-3mm, extending 1000&#8217;s m over the seafloor. Here we propose that after mixing with seawater, the erupting fragmented material typically forms a negatively buoyant fountain. To explore their dynamics, we present a simple numerical model to describe the evolution of the eruption column and series of laboratory experiments of turbulent particle-laden fountains rising through a stratified water column. &#160;Our experiments show that at the top of the fountain, some of the erupted material collapses to the seafloor to form a pyroclastic flow. However, some of the buoyant water in the fountain may separate from the top of the fountain, to form a buoyant plume which can carry particles higher into the water column. Eventually this mixture will be arrested by the ambient stratification and intrudes into the water column. Subsequently, the particles settle from this intrusion to form a fall-type deposit.&#160;Quantification of the controls on the concurrent fall and flow deposits, and comparison with field observations, including from the 2012 eruption of Havre Volcano in the South Pacific, open the way to new understanding of submarine eruptions.</div>

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On simple models for gravity currents from moving sources

Cited by 2 publications

References 9 publications

The dynamics of impinging plumes from a moving source

The dynamics of impinging plumes from a moving source

Dynamics of deep-submarine explosive eruptions

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