The mechanism of sediment transport on bed forms

2020 ◽  
pp. 137-142
Author(s):  
J.C.C. De Ruiter
Keyword(s):  
Sediment Transport ◽  
Bed Forms

Upper-regime parallel lamination as the result of turbulent sediment transport and low-amplitude bed forms

Sedimentology ◽  
1989 ◽  
Vol 36 (1) ◽  
pp. 47-59 ◽  
Author(s):  
CHRIS PAOLA ◽  
STEPHEN M. WIELE ◽  
MARY A. REINHART
Keyword(s):  
Sediment Transport ◽  
Bed Forms ◽  
Low Amplitude

On the Prediction of Sediment Transport in Sewers with Deposits

1993 ◽  
Vol 27 (5-6) ◽  
pp. 69-80 ◽  
Author(s):  
Rob A. Kleijwegt
Keyword(s):  
Sediment Transport ◽  
Probabilistic Models ◽  
Basic Knowledge ◽  
Incipient Motion ◽  
Negative Effects ◽  
Deterministic Models ◽  
Improve Design ◽  
Sewer Systems ◽  
Cohesive Sediment Transport ◽  
Bed Forms

There is a need for models to predict the negative effects of sewer deposits in order to improve design, maintenance and operation of sewerage systems. The lack of success of deterministic sewer sediment models in the past is caused by a lack of basic knowledge, which causes unknown uncertainties in the model's results. The basic knowledge about non-cohesive sediment transport has been studied with laboratory experiments. This has resulted in an understanding of the non-cohesive sewer sediment transport and the related subjects of bed shear stress, incipient motion, bed forms and flow resistance. This understanding can be used in the development of deterministic models for sewer systems. However, the next objective will be to develop probabilistic models.

scholarly journals Formation of rhythmic sorted bed forms on the continental shelf: an idealised model

2011 ◽  
Vol 684 ◽  
pp. 475-508 ◽  
Author(s):  
Tomas Van Oyen ◽  
Huib de Swart ◽  
Paolo Blondeaux
Keyword(s):  
Sediment Transport ◽  
Coarse Grained ◽  
Qualitative Comparison ◽  
Fine Sediments ◽  
Bed Elevation ◽  
Steady Current ◽  
Bed Forms ◽  
Current Shift ◽  
Idealised Model ◽  
Sediment Mixture

AbstractAn idealised model is presented to study the formation of sorted bed forms generated by a wind-driven along-shore current. The study employs a linear stability analysis to describe the time development of perturbations of both bottom composition and bed elevation, superimposed on a flat bed composed of a sediment mixture homogeneously distributed in space. The model considers both bed and suspended loads and takes into account the averaged influence of waves on the flow field and the transport of sediment. The results show that the positive coupling between waves, along-shore current and the erodible heterogeneous bed leads to the amplification of two modes, which exhibit distinct characteristics. A first mode is found to be dominant when moderate hydrodynamic conditions are considered and is primarily amplified by the convergence of sediment transport induced by the changes in the bed elevation. This mode has wavelengths of the order of hundred metres and has coarse (fine) sediments in its troughs (crests). By increasing the height of the waves and/or the strength of the steady current, the second mode can become dominant. This mode is characterised by shorter wavelengths and results from the interaction between the convergence of sediment transport related to changes in the bottom composition and that induced by perturbations of the bed elevation. These bed features can have an up-current or a down-current shift between the centre of the coarse-grained bands and the trough of the bottom wave. Typical growth times of the amplified features are of the order of hundreds of days and the migration rates, in the direction of the along-shore current, range between 0.1 and 10 m per day. A qualitative comparison of the model results with field observations indicates that the generation of two distinct modes provides a possible explanation for the broad range of characteristics of the natural bed features.

A Laboratory Study of Sediment Transport in Free Surface Flow

2005 ◽  
Author(s):  
Alfred D. Parr
Keyword(s):  
Sediment Transport ◽  
Transport Phenomena ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Local Scour ◽  
Bridge Piers ◽  
Bed Load ◽  
Dimension Lumber ◽  
Hands On ◽  
Bed Forms

This paper discusses an undergraduate fluid mechanics laboratory session. The lab allows the students to observe various sediment transport phenomena in a hands-on manner. The experiments are performed in a glass-walled, tilting sediment flume. The following sediment transport phenomena are created and observed by the students — bed load, suspended load, bed forms (ripples, dunes, antidunes...), surface waves over various bed forms and local scour at flow obstructions including bridge piers and abutments. Students are able to observe local scour using PVC pipes for bridge piers and dimension lumber for abutment scour. Since the flume is 12.2-m long, a large group of students can spread out along both sides of the flume to observe bed forms and to perform local scour tests.

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