On the propagation of particulate gravity currents in circular and semi-circular channels partially filled with homogeneous or stratified ambient fluid

Zemach, T.; Chiapponi, L.; Petrolo, D.; Ungarish, Marius; Longo, Sandro; Federico, Vittorio Di

doi:10.1063/1.4995388

Cited by 11 publications

(3 citation statements)

References 41 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The resulting confined cross‐flow (i.e., gravity current) produces a spiraling coherent density SOV which advects down the mixing interface (see Movie ). The sediment particle dynamics of the gravity current (Zemach et al., 2017) may introduce additional complexities to this mechanism, the extents to which are unclear, and thus present an interesting topic for future research.…”

Section: Introductionmentioning

confidence: 99%

Impact of Density Gradients on the Secondary Flow Structure of a River Confluence

Duguay

Biron

Lacey

2022

Water Resources Research

View full text Add to dashboard Cite

A greater understanding of these structures is therefore of obvious interest. Four structures are often discussed: helical cells (secondary flow at the scale of the tributaries' widths), vertically orientated Kelvin-Helmholtz (KH) vortices (shear-induced instabilities along the mixing interface), episodic pulses (origins still not fully understood, see Sabrina et al. (2021)) and streamwise orientated vortices (SOVs). SOVs were first discovered in numerical models as a pair of back-to-back, counter-rotating SOVs flanking each side of the mixing interface (Constantinescu et al., 2011) and their development is generally attributed to the downwelling of superelevated water, in a process strengthened by planform curvature (Sukhodolov & Sukhodolova, 2019). Recently, however strongly coherent SOVs were directly observed in turbidity currents at the Coaticook-Massawippi confluence (Duguay et al., 2022), and numerical modeling showed these SOVs to be gravity currents, caused by a small density gradient Δρ of ≈0.5 kg/m 3 , being confined between the converging flows (Duguay et al., 2022). Gaining knowledge of how greater magnitudes of Δρ and/or a reversal in the direction of Δρ influence these SOVs is the first step towards a full understanding of these intriguing flow structures.Density gradients develop when differences in temperature, dissolved minerals, or suspended sediment concentrations are present across the mixing interface. Density gradients commonly occur (

show abstract

Section: Introductionmentioning

confidence: 99%

Impact of Density Gradients on the Secondary Flow Structure of a River Confluence

Duguay

Biron

Lacey

2022

Water Resources Research

View full text Add to dashboard Cite

show abstract

“…More complex models refer to particle-driven currents (Sparks et al 1993;Hogg, Ungarish & Huppert 2000;Zemach et al 2017;Lippert & Woods 2020). Sher & Woods (2017) described the relative importance of entrainment at the interface and particle sedimentation in controlling the run-out distance of short-lived GCs, and the influence of an up-slope boundary has been considered by Ottolenghi et al (2016), Martin et al (2020) and De Falco et al (2021).…”

Section: Introductionmentioning

confidence: 99%

Experimental study on radial gravity currents flowing in a vegetated channel

et al. 2022

Self Cite

View full text Add to dashboard Cite

We present an experimental study of gravity currents in a cylindrical geometry, in the presence of vegetation. Forty tests were performed with a brine advancing in a fresh water ambient fluid, in lock release, and with a constant and time-varying flow rate. The tank is a circular sector of angle $30^\circ$ with radius equal to 180 cm. Two different densities of the vegetation were simulated by vertical plastic rods with diameter $D=1.6\ \textrm{cm}$ . We marked the height of the current as a function of radius and time and the position of the front as a function of time. The results indicate a self-similar structure, with lateral profiles that after an initial adjustment collapse to a single curve in scaled variables. The propagation of the front is well described by a power law function of time. The existence of self-similarity on an experimental basis corroborates a simple theoretical model with the following assumptions: (i) the dominant balance is between buoyancy and drag, parameterized by a power law of the current velocity $\sim |u|^{\lambda-1}u$ ; (ii) the current advances in shallow-water conditions; and (iii) ambient-fluid dynamics is negligible. In order to evaluate the value of ${\lambda}$ (the only tuning parameter of the theoretical model), we performed two additional series of measurements. We found that $\lambda$ increased from 1 to 2 while the Reynolds number increased from 100 to approximately $6\times10^3$ , and the drag coefficient and the transition from $\lambda=1$ to $\lambda=2$ are quantitatively affected by D, but the structure of the model is not.

show abstract

“…Such behaviour has never been observed and is unphysical, consequently frontal mixing cannot be included in a top-hat model. Instead, it has been found necessary to include empirical factors which crudely capture the effect of mixing (Zemach et al, 2017), but this is a suboptimal approach because the effect of mixing increases over time in a manner depending on the dynamics. Instead, we can incorporate mixing or erosion in the head by taking σ uφ = 1 (in this paragraph all values are evaluated at x = x f ).…”

Section: Properties Of the Frontmentioning

confidence: 99%

Self-stratifying turbidity currents

Skevington¹,

Dorrell²

2022

Preprint

View full text Add to dashboard Cite

Turbidity currents, submarine currents driven by the excess density of suspended particles, carry vast quantities of sediment and nutrients from the continental margins to the deep ocean. Due to their vast scale and extreme aspect ratio, simplified depth-or channel-averaged models are required to capture their dynamics. The inclusion of vertical structure (profiles of velocity, depth, and turbulent kinetic energy) and levee overspill in these models is in its infancy, and we demonstrate their importance in this study. We present a new channel-averaged model that supports an arbitrary evolving vertical structure and a compatible closure for the levee overspill. By examining this new model, connections between the vertical structure and the internal turbulent processes are revealed. Additionally, we find new requirements for models of the front of the current, demonstrating a connection between the vertical structure of the body and the mixing and erosion in the head.In our new framework we build a full 'proof of concept' model to illuminate the substantial effect that vertical structure and levee overspill have on the current. In this model, the vertical structure changes as part of the evolution of the current: it self-stratifies. Quasi equilibrium solutions are constructed, where the entrainment causes deepening. These solutions are not stable, but rather weekly unstable and connected to a slowly evolving manifold: we expect most environmental currents to evolve within such a manifold. Equilibrium solutions are not stable either, the levee overspill removing the dilute, low momentum fluid, which rejuvenates the flow, and this can cause a positive feedback loop where the fluid becomes increasingly concentrated. Finally, we present some simulations of the Congo system, for the first time capturing a current that travels out to the end of the levees in a channel-averaged model.

show abstract

On the propagation of particulate gravity currents in circular and semi-circular channels partially filled with homogeneous or stratified ambient fluid

Cited by 11 publications

References 41 publications

Impact of Density Gradients on the Secondary Flow Structure of a River Confluence

Impact of Density Gradients on the Secondary Flow Structure of a River Confluence

Experimental study on radial gravity currents flowing in a vegetated channel

Self-stratifying turbidity currents

Contact Info

Product

Resources

About