Computational Dam-Break Hydraulics over Erodible Sediment Bed

Cao, Zhixian; Pender, Gareth; Wallis, Stephen George; Carling, Paul A.

doi:10.1061/(asce)0733-9429(2004)130:7(689)

Cited by 316 publications

(383 citation statements)

References 21 publications

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“…The comparison also reveals that the rapid sediment entrainment causes the fluid flow to become bulked at the initial stage (e.g., Figure 1a It is also noted that the initial wave front for the movable bed is slightly slower than that over the fixed bed (Figure 2a), but as time increases the wave front with sediment transport is progressively closer to that over the fixed bed (Figure 2b), and then it oversteps the wave front without sediment transport (Figure 2c). This is also manifested by the numerical studies of (Cao et al, 2004;Wu and Wang, 2007).…”

Section: Effects Of Sediment Transportmentioning

confidence: 72%

“…The insights obtained are useful but inevitably have limitations. In recent decades, efforts have been made to model extreme flood events to demonstrate both flow dynamics and geomorphic processes (Cao et al, 2004;Capart and Young, 1998;Fraccarollo and Capart, 2002;Guan et al, 2014;Li and Duffy, 2011;Li et al, 2014;Simpson and Castelltort, 2006;Wong et al, 2014;Wu and Wang, 2007;Xia et al, 2010). Existing numerical work mostly focused on modelling of small-scale flow events or analysis of idealised dam-break hydraulics.…”

Section: Introductionmentioning

confidence: 99%

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Multiple effects of sediment transport and geomorphic processes within flood events: Modelling and understanding

Guan

Wright

Sleigh

2015

International Journal of Sediment Research

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Flood events can induce considerable sediment transport which in turn influences flow dynamics. This study investigates the multiple effects of sediment transport in floods through modelling a series of hydraulic scenarios, including small-scale experimental cases and a full-scale glacial outburst flood. A non-uniform, layer-based morphodynamic model is presented which is composed of a combination of three modules: a hydrodynamic model governed by the two-dimensional shallow water equations involving sediment effects; a sediment transport model controlling the mass conservation of sediment; and a bed deformation model for updating the bed elevation. The model is solved by a second-order Godunov-type numerical scheme. Through the modelling of the selected sediment-laden flow events, the interactions of flow and sediment transport and geomorphic processes within flood events are elucidated. It is found that the inclusion of sediment transport increases peak flow discharge, water level and water depth in dam-break flows over a flat bed. For a partial dam breach, sediment material has a blockage effect on the flood dynamics. In comparison with the 'sudden collapse' of a dam, a gradual dam breach significantly delays the arrival time of peak flow, and the flow hydrograph is changed similarly. Considerable bed erosion and deposition occur within the rapid outburst flood, which scours the river channel severely. It is noted that the flood propagation is accelerated after the incorporation of sediment transport, and the water level in most areas of the channel is reduced.

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Section: Effects Of Sediment Transportmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Multiple effects of sediment transport and geomorphic processes within flood events: Modelling and understanding

Guan

Wright

Sleigh

2015

International Journal of Sediment Research

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“…Bed load sediment transport capacity e c is determined by local flow regime. The empirical parameter  represents the difference between the near-bed concentration and the depth-averaged concentration of sediment; its value is determined by the method in Cao et al [15]. The bed load sediment transport capacity …”

Section: Model Closurementioning

confidence: 99%

“…It is recognized that environmental flows may induce active sediment transport and morphological evolution, which in turn modify the flows. One of the most telling cases is dam-break flow over an erodible sediment bed [14][15][16]. To date, however, most studies using AMR have been limited to cases either without involving sediment transport at all [4, [9][10][11]13,17] or featuring the assumption of sediment transport capacity, which is not normally justified.…”

Section: Introductionmentioning

confidence: 99%

“…Equally critically, it features the assumption of sediment transport capacity, i.e., sediment transport rate is assumed to be determined exclusively by local flow regime. However, this assumption is not generally justified, especially in highly unsteady flows such as dam-break flows over mobile beds [15]. Zhang and Wu [19] developed a hydrodynamic and sediment transport model based on a multiple-level quadtree mesh with local refinement for the dam-break floods over mobile bed.…”

Section: Introductionmentioning

confidence: 99%

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Coupled flood and sediment transport modelling with adaptive mesh refinement

Huang

Cao

Pender

et al. 2015

Sci. China Technol. Sci.

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Coupled flood and sediment transport modelling in large-scale domains has for long been hindered by the high computational cost. Adaptive mesh refinement is one of the viable ways to solving this problem without degrading the accuracy. This goal can be accomplished through mesh adaptation, e.g., mesh coarsening and refining based on the dynamic regime of the flow and sediment transport along with bed evolution. However, previous studies in this regard have been limited to cases either without involving sediment transport or featuring flow-sediment-bed decoupling and the assumption of sediment transport capacity, which are not generally justified. Here, a coupled hydrodynamic and non-capacity sediment transport model is developed on adaptive non-uniform rectangular mesh. The proposed model is validated against experimental tests and numerical results based on the fixed meshes. It is demonstrated that the proposed model can properly capture shock waves, resolve the wetting/drying transition and reproduce morphological evolution. Compared with models based on the fixed meshes, the proposed model features great advantage in computational efficiency and holds promise for wide applications.shallow water flow, sediment transport, adaptive mesh Citation:Huang W, Cao Z X, Pender G, et al. Coupled flood and sediment transport modelling with adaptive mesh refinement.

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Entrainment of bed material by Earth‐surface mass flows: Review and reformulation of depth‐integrated theory

Iverson

Ouyang

2015

Reviews of Geophysics

251

142

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Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass and momentum conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must, in general, satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

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Computational Dam-Break Hydraulics over Erodible Sediment Bed

Cited by 316 publications

References 21 publications

Multiple effects of sediment transport and geomorphic processes within flood events: Modelling and understanding

Multiple effects of sediment transport and geomorphic processes within flood events: Modelling and understanding

Coupled flood and sediment transport modelling with adaptive mesh refinement

Entrainment of bed material by Earth‐surface mass flows: Review and reformulation of depth‐integrated theory

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