Polydisperse particle-driven gravity currents

Harris, Thomas C.; Hogg, Andrew J.; Huppert, Herbert E.

doi:10.1017/s0022112002002379

Cited by 48 publications

(53 citation statements)

References 22 publications

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“…This is beneficial for capturing the important flow features. This model has been used extensively in understanding turbidity current flow characteristics (Harris et al, 2001;Hogg, 2006), including the effects of modelling polydisperse suspensions (Harris et al, 2002;Garcia, 1994) and the effects of external flow (Hallworth et al, 1998). The model used in this paper is based upon the single layer shallow water model of Bonnecaze et al (1993).…”

Section: Modelmentioning

confidence: 99%

Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

Parkinson¹,

Funke²,

Piggott³

et al. 2017

Geosci. Model Dev.

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Abstract. Turbidity currents are one of the main drivers of sediment transport from the continental shelf to the deep ocean. The resulting sediment deposits can reach hundreds of kilometres into the ocean. Computer models that simulate turbidity currents and the resulting sediment deposit can help us to understand their general behaviour. However, in order to recreate real-world scenarios, the challenge is to find the turbidity current parameters that reproduce the observations of sediment deposits. This paper demonstrates a solution to the inverse sediment transportation problem: for a known sedimentary deposit, the developed model reconstructs details about the turbidity current that produced the deposit. The reconstruction is constrained here by a shallow water sediment-laden density current model, which is discretised by the finite-element method and an adaptive time-stepping scheme. The model is differentiated using the adjoint approach, and an efficient gradientbased optimisation method is applied to identify the turbidity parameters which minimise the misfit between the modelled and the observed field sediment deposits. The capabilities of this approach are demonstrated using measurements taken in the Miocene Marnoso-arenacea Formation (Italy). We find that whilst the model cannot match the deposit exactly due to limitations in the physical processes simulated, it provides valuable insights into the depositional processes and represents a significant advance in our toolset for interpreting turbidity current deposits.

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Section: Modelmentioning

confidence: 99%

Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

Parkinson¹,

Funke²,

Piggott³

et al. 2017

Geosci. Model Dev.

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“…The importance of multiple grain sizes is emphasized (e.g., Harris et al 2002) in developing realistic flow models, as they occur in most natural flows and strongly influence model results. Felletti proposed that the anisotropy of magnetic susceptibility (AMS) is a valuable tool to estimate paleocurrents in turbidites (Dall'Olio et.…”

Section: (B) Supercritical-flow Dynamics and Depositsmentioning

confidence: 99%

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

165

117

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Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than , 0.6u. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (, 0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces

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“…For α = 0 and β (i) = 0, (i = 1, 2) the model becomes the formulation of bidisperse particle-driven gravity currents in the rectangular channels (Harris et al [3]). Indeed, the equations and the boundary conditions are identical, however Harris et.…”

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

Bidisperse Particle-Driven Gravity Currents in Power-Law Cross-Section Channels

Zemach¹

2017

Topical Problems of Fluid Mechanics 2017

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Particle-driven gravity currents are suspensions of dense particles that spread into an ambient fluid due to the difference between the density of the suspension and that of the ambient fluid. In most of the analytical works, it has been assumed that the suspension of particles possess a single settling velocity. However in many situations this is a considerable simplification and in virtually all real situations there is a range of particle sizes, and hence settling velocities. In the present work we consider the propagation of a high-Reynolds-number gravity current driven by a bi-disperse distribution of two types of particles in fluid of density ρ a propagating along a channel into an ambient fluid of the density ρ a . The bottom and top of the channel are at z = 0, H and the cross-section is given by the power-law f(z). The flow is modeled by the one-layer shallow-water equations. We solve the problem by the finite-difference numerical code to present typical height h(x,t), velocity u(x,t) and volume fractions of particles profiles. We demonstrate that in some regimes it is sufficient to deduce the behavior of the suspension to the corresponding monodisperse suspension of average settling velocity. The numerical results are confirmed by recent experimental results.

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Polydisperse particle-driven gravity currents

Cited by 48 publications

References 22 publications

Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

Key Future Directions For Research On Turbidity Currents and Their Deposits

Bidisperse Particle-Driven Gravity Currents in Power-Law Cross-Section Channels

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