Large Eddy Simulation of Lock-Exchange Flow in a Curved Channel

Mahdinia, Mani; Firoozabadi, Bahar; Farshchi, Mohammad; Varnamkhasti, A. Ghasemi; Afshin, Hossein

doi:10.1061/(asce)hy.1943-7900.0000482

Cited by 21 publications

(30 citation statements)

References 56 publications

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“…The nature of the helical flow field in submarine channels has generated considerable controversy over the past few years, and experimental and numerical research have shown apparently contradictory data, with the helical cell being documented as either reversed in orientation at bend apices relative to river channels, or ‘river‐like’, with basal flow directed towards the inner bank (Kassem & Imran, ; Corney et al ., , ; Keevil et al ., , ; Imran et al ., ; Islam et al ., ; Mahdinia et al ., ). In addition, recent field data from an active channel in the Black Sea (Parsons et al ., ) and a slope channel (gradient ca 0·01) at outcrop (Pyles et al ., , ) have demonstrated that reversed flow can occur in submarine channels.…”

Section: Introductionmentioning

confidence: 97%

Three‐dimensional gravity‐current flow within a subaqueous bend: Spatial evolution and force balance variations

et al. 2013

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The nature of three-dimensional flow in submarine channel bends is poorly understood, largely due to the absence of detailed data from natural channels. Herein, data from density-driven flows in a large reservoir on the Huanghe (Yellow) River are presented showing the spatio-temporal variation of flow around a subaqueous bend. The data demonstrate for the first time that reversed helical flow, relative to that found in river channel bends, can occur from the centrifugal forcing of flow, even when the Coriolis force acts in the opposite direction. The data also suggest that reversed helical flow fields in submarine channels may be more frequent than currently estimated, notably for bends where Coriolis and centrifugal forces combine in the same direction. In addition, this study provides the first field evidence suggesting that sinuous submarine channels can exhibit an asymmetry in helical flow orientation between left and right-turning bends, which will have major implications for the morphodynamics of submarine channels, their resultant patterns of sedimentation and, ultimately, the distribution of depositional units across submarine fan systems.

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Section: Introductionmentioning

confidence: 97%

Three‐dimensional gravity‐current flow within a subaqueous bend: Spatial evolution and force balance variations

et al. 2013

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“…Subsequently, a variety of studies including numerical and experimental models [ Keevil et al ., ; Corney et al ., ; Islam and Imran , ; Cossu and Wells , ; Abad et al ., ; Giorgio Serchi et al ., ; Huang et al ., ; Mahdinia et al ., ; Janocko et al ., ], measurements of field‐scale submarine density currents [ Parsons et al ., ], and examination of ancient deposits in the rock record [ Pyles et al ., ] have demonstrated the occurrence of both river‐like and river‐reversed helical flows in submarine channel bends as well as the occurrence of multiple vertically stacked helical flow cells [e.g., Rosovskii , 1957; Imran et al ., ; Islam and Imran , ; Giorgio Serchi et al ., ]. Having established that a variety of helical flow patterns are possible, the debate has now moved on to understanding what controls the orientation of helical flow in submarine density currents and therefore how common different modes of helical circulation are in natural systems [ Abad et al ., ; Giorgio Serchi et al ., ] and examining the implications of such reversals for channel morphology [ Peakall et al ., ; Amos et al ., ; Darby and Peakall , ; Janocko et al ., ].…”

Section: Introductionmentioning

confidence: 98%

Driven around the bend: Spatial evolution and controls on the orientation of helical bend flow in a natural submarine gravity current

et al. 2014

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Submarine channel systems transport vast amounts of terrestrial sediment into the deep sea.Understanding the dynamics of the gravity currents that create these systems, and in particular, how these flows interact with and form bends, is fundamental to predicting system architecture and evolution. Bend flow is characterized by a helical structure and in rivers typically comprises inwardly directed near-bed flow and outwardly directed near-surface flow. Following a decade of debate, it is now accepted that helical flow in submarine channel bends can exhibit a variety of structures including being opposed to that observed in rivers. The new challenge is to understand what controls the orientation of helical flow cells within submarine flows and determines the conditions for reversal. We present data from the Black Sea showing, for the first time, the three-dimensional velocity and density structure of an active submarine gravity current. By calculating the forces acting on the flow, we evaluate what controls the orientation of helical flow cells. We demonstrate that radial pressure gradients caused by across-channel stratification of the flow are more important than centrifugal acceleration in controlling the orientation of helical flow. We also demonstrate that nonlocal acceleration of the flow due to topographic forcing and downstream advection of the cross-stream flow are significant terms in the momentum balance. These findings have major implications for conceptual and numerical models of submarine channel dynamics, because they show that three-dimensional models that incorporate across-channel flow stratification are required to accurately represent curvature-induced helical flow in such systems.

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“…Felix [2001] proposed a two-dimensional turbulence model to address the development of turbidity current. In the same line, the large eddy simulation along with direct numerical simulation was also applied to simulate the turbidity currents [Mahdinia et al, 2011;Dutta et al, 2012]. On the other hand, as a new trend in simulation of gravity currents, the application of the thermal lattice Boltzmann method was also reported [Lizhong et al, 2011;Prestininzi et al, 2013].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic analysis of fully developed turbidity currents over plane beds based on self‐preserving velocity and concentration distributions

et al. 2015

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This paper presents a hydrodynamic analysis for the fully developed turbidity currents over a plane bed stemming from the classical three‐equation model (depth‐averaged fluid continuity, sediment continuity, and fluid momentum equations). The streamwise velocity and the concentration distributions preserve self‐similarity characteristics and are expressed as single functions of vertical distance over the turbidity current layer. Using the experimental data of turbidity and salinity currents, the undetermined coefficients and exponents are approximated. The proposed relationships for velocity and concentration distributions exhibit self‐preserving characteristics for turbidity currents. The depth‐averaged velocity, momentum, and energy coefficients are thus obtained using the proposed expression for velocity law. Also, from the expressions for velocity and concentration, the turbulent diffusivity and the Reynolds shear stress distributions are deduced with the aid of the diffusion equation of sediment concentration and the Boussinesq hypothesis. The generalized equation of unsteady nonuniform turbidity current is developed by using the velocity and concentration distributions in the moments of the integral scales over the turbidity current layer. Then, the equation is applied to analyze the gradually varied turbidity currents considering closure relationships for boundary interaction and shear velocity. The streamwise variations of current depth, velocity, concentration, reduced sediment flux, and Richardson number are presented. Further, the self‐accelerating and depositional characteristics of turbidity currents including the transitional feature from erosional to depositional modes are addressed. The effects of the streamwise bed slope are also accounted for in the mathematical derivations. The results obtained from the present model are compared with those from the classical model.

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Large Eddy Simulation of Lock-Exchange Flow in a Curved Channel

Cited by 21 publications

References 56 publications

Three‐dimensional gravity‐current flow within a subaqueous bend: Spatial evolution and force balance variations

Three‐dimensional gravity‐current flow within a subaqueous bend: Spatial evolution and force balance variations

Driven around the bend: Spatial evolution and controls on the orientation of helical bend flow in a natural submarine gravity current

Hydrodynamic analysis of fully developed turbidity currents over plane beds based on self‐preserving velocity and concentration distributions

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