Sediment Transport, Part III: Bed forms and Alluvial Roughness

Rijn, van; Leo, Chin Jian

doi:10.1061/(asce)0733-9429(1984)110:12(1733)

Cited by 656 publications

(565 citation statements)

References 19 publications

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“…This diagram is a review of Van Rijn's diagram ( VAN RIJN, 1984), which considers the influence of shear stresses on the occurrence and dimensions of bedforms as a basic element of this approach and relates the average dimensionless grain size (d 50 *) with the mobility parameter (θ'). Figure 9 shows the application of these parameters to the tested density currents and to the used bedforms.…”

Section: Van Den Berg and Van Gelder (1993)mentioning

confidence: 99%

Prediction of the bedforms generated by density currents based on fluvial phase diagrams

Koller

Borges

Puhl

et al. 2017

RBRH

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Density currents, whose movement takes place by the density difference between the flow and the ambient fluid around it, can interact with the substract generating bedforms similar to the fluvial environments. However, there are no specific bedform phase diagrams capable to predict this type of phenomenon. This study aims to compare the prediction of fluvial bedforms phase diagram with those generated by experimental saline currents. Bedforms were generated in two-dimensional tilting plexiglass flume submerged in a larger tank filled with water with three different mobile beds and varied values of discharge and salt concentration. It was observed three types of bedform (lower plane bed, ripples and dunes), which, with the concomitant calculation of hydrodynamic parameters (mean velocity, energy and mobility) allowed the use of the phase diagram. It was observed that the fluvial phase diagrams did not present good predictions for bedforms generated by density currents. This fact is associated to the hydrodynamics differences (velocity and concentration profiles) and the limitation of the dimensional parameters in the extrapolation of results. Therefore, it is indicated the need to draw up a proper phase diagram to density currents. Keywords: Density current; Bedforms; Physical modeling; Mobile bed; Bedform phase diagram. RESUMOAs correntes de densidade, cujo movimento ocorre pela diferença de massa específica entre o escoamento e o fluido ambiente ao seu redor, podem interagir com o substrato gerando formas de fundo, similares às encontradas em ambientes fluviais. Entretanto não existem diagramas de previsão específicos correspondentes para esse tipo de fenômeno. Assim, este trabalho visa comparar a ocorrência das formas de fundo fluviais previstas nos diagramas de previsão com aquelas geradas por correntes de densidade salinas obtidas experimentalmente. As formas de fundo foram geradas em um canal bidimensional de declividade variável, preenchido por água, com três composições de leito móvel e diferentes valores de vazão, massa especifica e inclinação. Três formas de fundo foram identificadas (leito plano inferior, ondulações e dunas), as quais, juntamente com o cálculo de parâmetros hidrodinâmicos permitiram a utilização dos diagramas fluviais. Verificou-se que os diagramas fluviais não apresentaram boas previsões das formas de fundo geradas por correntes de densidade. A esse fato são atribuídas as diferenças hidrodinâmicas dos escoamentos (perfis de velocidade e concentração) e, também, à limitação dos parâmetros dimensionais na extrapolação dos resultados. Dessa forma, indica-se a necessidade de se elaborar um diagrama de previsão próprio adaptado a estas correntes.Palavras-chave: Corrente de densidade; Formas de leito; Modelagem física; Leito móvel; Diagrama de previsão.

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Section: Van Den Berg and Van Gelder (1993)mentioning

confidence: 99%

Prediction of the bedforms generated by density currents based on fluvial phase diagrams

Koller

Borges

Puhl

et al. 2017

RBRH

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“…Bedload measurement is particularly challenging due to its variability both spatially and temporally. In a series of articles, van Rijn [12][13][14] conducted detailed analyses on bedload transport of large-grained non-cohesive sediments of uniform shape, size, and density to quantify the parameters describing bedload movement. Despite similar efforts including other researchers, understanding bedload transport in relation to deposition patterns in different roughness remained unattended.…”

Section: Mode Of Sediment Transportmentioning

confidence: 99%

Hydrodynamic investigation of fluvial sediment transport with Soil Protrusion Apparatus (SPA)

Jayaratne

Salim

2014

Open Engineering

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Abstract:In order to understand sediment transport process based on knowledge of their soil properties and hydrodynamic behaviour a series of 2D laboratory controlled small-scale experiments were conducted using the Ahlborn sediment mobile bed tank (4.0×0.6×0.2 m). Experiments were conducted in smooth and rough bed conditions with purposely-built Soil Protrusion Apparatus (SPA) to measure the basic parameters on which erosion depends. Sediment deposition patterns in equilibrium stage associated with different bed roughness and particle size distributions were fundamentally investigated. Extended physical modelling of crescent zones also included analysing their grain size distribution. Dimensional analysis and multiple linear regression methods were employed to derive a simple empirical relationship for erosion rate (ER) in terms of the shear stress (τs), average grain diameter (d 50 ) and soil protrusion (z) for smooth and rough sediment bed conditions. These analyses also suggest ways to refine empirical models, examining transport rates to explore the limits of erosion and deposition influences in shallow flow conditions.

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“…Van Rijn, 1984] which is defined at a reference elevation whereas, for cohesive sediments, the Krone-Partheniades relation relates the erosion rate to the excess bed shear stress minus the resistance of the bed to erosion, which varies as a function of mud composition and consolidation state. The deposition flux (D) is calculated as the product of settling velocity W s and the near bed concentration.…”

Section: The Telemac Systemmentioning

confidence: 99%

A large scale morphodynamic process-based model of the Gironde estuary

Villaret¹,

Huybrechts²,

Davies³

2012

NCK-days 2012: Crossing Borders in Coastal Research: Jubilee Conference Proceedings NCK-days 2012

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We present here our effort to develop a morphodynamic model of the Gironde estuary, using a process-based approach. In this complex and strongly dynamical environment, internal coupling between the flow (Telemac-2d) and sediment transport models (Sisyphe) allows the representation of detailed sediment processes and interactions with the bed, using a bed roughness feedback method. In this complex and highly heterogeneous environment, the sediment bed composition had to be schematized assuming 3 classes of bed material. Model results could be further improved by accounting for the cohesive sediment (consolidation processes). Thanks to parallelization of the codes, the simulation takes only 18 hrs on 8 processors (linux station) to calculate the 5-year bed evolution, at the basin scale (150 km).

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Sediment Transport, Part III: Bed forms and Alluvial Roughness

Cited by 656 publications

References 19 publications

Prediction of the bedforms generated by density currents based on fluvial phase diagrams

Prediction of the bedforms generated by density currents based on fluvial phase diagrams

Hydrodynamic investigation of fluvial sediment transport with Soil Protrusion Apparatus (SPA)

A large scale morphodynamic process-based model of the Gironde estuary

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