On particle fountains in a stratified environment

Newland, Eric L; Woods, Andrew W.

doi:10.1017/jfm.2021.295

Cited by 4 publications

(8 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the time-averaged image, we can see that the model estimates of the centreline and radius of a single-phase fountain show very good agreement with the morphology of the particle fountain in this regime. This observation is consistent with observations of similar flows in various studies (Mingotti & Woods 2016;Newland & Woods 2021;James et al 2022).…”

Section: Qualitative Observationssupporting

confidence: 94%

“…For each particle size in our experiments, we estimate there to be a variation of size about the mean of, σ ≈ ±15 %, calculated from the particle size range in Washington Mills SIC Particle Size Guide. Although the particles are not spherical, we use Stokes law to estimate the vertical fall speed of the particles, v s , and control experiments carried out in previous studies (Mingotti & Woods 2019Newland & Woods 2021) show that the measured values of the sedimentation speeds are in good agreement with the Stokes fall speed estimate. The dilute particle-fluid suspension, with particle volume concentration C 0 typically 2.5 %, is stirred continuously and supplied to the injection nozzle using a Watson Marlow peristaltic pump at a constant volumetric flow rate, Q 0 .…”

Section: Experimental Set-upmentioning

confidence: 77%

See 1 more Smart Citation

On particle fountains in a crossflow

Newland

Woods

2023

J. Fluid Mech.

View full text Add to dashboard Cite

We present new experiments of particle-laden turbulent fountains in a uniform horizontal crossflow, $u_a$ , with momentum flux, $M_0$ , and buoyancy flux, $B_0$ . We use the ratio, $P$ , of the crossflow speed to the characteristic fountain speed, $M_0^{-1/4}|B_0|^{1/2}$ , and the ratio $U$ , of the Stokes fall speed of the particles, $v_s$ , to the characteristic fountain speed, to characterise the dynamics of a particle fountain in a crossflow. We find that the dynamics of these particle fountains can be categorised into three distinct regimes. In regime I when the fall speed of the particles is small in comparison with the characteristic fountain speed ( $U\ll 1$ ), the particles remain well-coupled to the fountain fluid and the flow essentially behaves as a single-phase fountain in a crossflow. In the transitional regime II ( $0.1< U<1$ ), when the fall speed of particles is comparable to the characteristic fountain speed, we observe some particles separating from the fountain fluid during the descent of the flow which leaves some fluid neutrally buoyant. As $U>1$ (regime III), we observe particles separating from the fountain as it rises from the source. We measure the average dispersal distance of the particles and the speed of the descending particles as a function of $U$ and $P$ and compare these results with models of a single-phase fountain in a crossflow. We build a regime diagram to describe the effect of $U$ and $P$ on the flow dynamics and consider our work in the context of deep-submarine volcanic eruptions.

show abstract

Section: Qualitative Observationssupporting

confidence: 94%

Section: Experimental Set-upmentioning

confidence: 77%

On particle fountains in a crossflow

Newland

Woods

2023

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…We list the median particle length, , alongside the estimates of in table 1 for the range of particles sizes used in this study. To estimate the vertical fall speed of the particles, , we use Stokes law such that This approximation is based on the assumption that the particles are spherical in shape, however previous studies of particle-laden flows that use the same silicon carbide particles, which are stated to be blocky/hexagonal in shape, have shown that the measured sedimentation speed shows good agreement with the estimates based on Stokes law (Mingotti & Woods 2015; Newland & Woods 2021). We list the estimates of as a function of particle size, , in table 1 alongside the error in the fall speed associated with the variation in particle size, , which are consistent with measurements of the fall speeds of the same particles presented in Mingotti & Woods (2015).…”

Section: Methodsmentioning

confidence: 99%

The dynamics of impinging plumes from a moving source

Newland,

Woods

2024

J. Fluid Mech.

View full text Add to dashboard Cite

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.

show abstract

“…Note that with very weak eruptions, the stratification would begin to have an impact on the height of rise (Bloomfield and Kerr, 1998;Newland and Woods, 2021;Turner, 1966).…”

Section: Source Conditionsmentioning

confidence: 99%

“…Using a model for turbulent entrainment into a jet (Turner, 1979;Woods, 2010) we present new calculations which suggests this occurs within a few 10's m above the source. The subsequent motion is essentially that of a turbulent, particle-laden fountain, whose bulk density exceeds that of the surrounding seawater, but in which the water is hot and hence of lower density (Allen and McPhie, 2009;Barreyre et al, 2011;Cashman and Fiske, 1991;Head III and Wilson, 2003;Kokelaar and Busby, 1992;Newland and Woods, 2021;Palmer and Ernst, 1998). The ascent of this negatively buoyant fountain is gradually arrested by gravity and the majority of the erupting material is likely to collapse back to the seafloor.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of deep-submarine explosive eruptions

Newland

Mingotti

Woods

2022

Preprint

View full text Add to dashboard Cite

<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>

show abstract

On particle fountains in a stratified environment

Abstract: Abstract

Cited by 4 publications

References 30 publications

On particle fountains in a crossflow

On particle fountains in a crossflow

The dynamics of impinging plumes from a moving source

Dynamics of deep-submarine explosive eruptions

Contact Info

Product

Resources

About