Transport rate under irregular sheet flow conditions

Dibajnia, Mohammad; Watanabe, Akira

doi:10.1016/s0378-3839(98)00034-9

Cited by 48 publications

(36 citation statements)

References 8 publications

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“…1). As remarked by Dibajnia and Watanabe (1998), the exchange of sediments between the two half cycles can also depend on the degree of asymmetry, i.e., on the values of T pc and T pt , because it changes the time available for sediment settling. In order to describe this process in the model we have assumed that T i in the Eq.…”

Section: New Semi-unsteady Modelmentioning

confidence: 99%

“…The Dibajnia and Watanabe (1998) experiments -DW98 -have been conducted in sheet flow conditions in the OWT of University of Tokyo. The velocity time series generated in the OWT was obtained by measuring the near bottom velocities of shoaling irregular waves (corresponding to two types of power spectrum) over a uniform slope in a wave flume.…”

Section: Application Of the New Semi-unsteady Model To Regular And Irmentioning

confidence: 99%

“…In the computations performed with the new formula, two types of representative waves were considered: a 2nd order Stokes wave and a sinus wave. For each test condition, the parameters of the representative wave (including its skewness) were computed in terms of the significant values because, as stated by Dibajnia and Watanabe (1998), sediment is supposed to be transported mainly by the larger velocities. The results obtained for the sediment transport rate are compared with the measurements in Fig.…”

Section: Application Of the New Semi-unsteady Model To Regular And Irmentioning

confidence: 99%

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Sand transport under combined current and wave conditions: A semi-unsteady, practical model

Silva

Temperville

Santos

2006

Coastal Engineering

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For the general purposes of morphodynamic computations in coastal zones, simple formula-based models are usually employed to evaluate sediment transport. Sediment transport rates are computed as a function of the bottom shear stress or the near bed flow velocity and it is generally assumed that the sediment particles react immediately to changes in flow conditions. It has been recognized, through recent laboratory experiments in both rippled and plane bed sheet flow conditions that sediment reacts to the flow in a complex manner, involving non-steady processes resulting from memory and settling/entrainment delay effects. These processes may be important in the cross-shore direction, where sediment transport is mainly caused by the oscillatory motions induced by surface short gravity waves.The aim of the present work is to develop a semi-unsteady, practical model, to predict the total (bed load and suspended load) sediment transport rates in wave or combined wave-current flow conditions that are characteristic of the coastal zone. The unsteady effects are reproduced indirectly by taking into account the delayed settling of sediment particles. The net sediment transport rates are computed from the total bottom shear stress and the model takes into account the velocity and acceleration asymmetries of the waves as they propagate towards the shore.A comparison has been carried out between the computed net sediment transport rates with a large data set of experimental results for different flow conditions (wave-current flows, purely oscillatory flow, skewed waves and steady currents) in different regimes (plane bed and rippled bed) with fine, medium and coarse uniform sand. The numerical results obtained are reasonably accurate within a factor of 2. Based on this analysis, the limits and validity of the present formulation are discussed.

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Section: New Semi-unsteady Modelmentioning

confidence: 99%

Section: Application Of the New Semi-unsteady Model To Regular And Irmentioning

confidence: 99%

Section: Application Of the New Semi-unsteady Model To Regular And Irmentioning

confidence: 99%

See 1 more Smart Citation

Sand transport under combined current and wave conditions: A semi-unsteady, practical model

Silva

Temperville

Santos

2006

Coastal Engineering

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“…Experimental studies to investigate sheet flow have been conducted primarily in oscillatory flow tunnels [Horikawa et al, 1982;Ribberink and Al-Salem, 1995;Dibajnia and Watanabe, 1998;Dohmen-Janssen et al, 2001;Ahmed and Sato, 2003;Wright, 2004a, 2004b;van der A et al, 2010;Ruessink et al, 2011;Dong et al, 2013], supplemented by wave flume studies Hanes, 2002, 2005;Chassagneux and Hurther, 2014]. A main outcome was the development of empirical formulas for the net sheet flow sediment transport aimed toward use in large-scale morphodynamic models [Drake and Calantoni, 2001;Hoefel and Elgar, 2003;Watanabe and Sato, 2004;Camenen and Larson, 2006;da Silva et al, 2006;Nielsen, 2006;Gonzalez-Rodriguez and Madsen, 2007;van der A et al, 2010.…”

Section: Introductionmentioning

confidence: 99%

A semianalytical model for sheet flow layer thickness with application to the swash zone

Lanckriet

Puleo

2015

JGR Oceans

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A new semianalytical model for the time-dependent thickness of the sheet flow layer that includes the effects of pressure gradients, bed slope, boundary layer growth, and bore turbulence is presented. The shear stress and boundary layer growth are computed using the boundary layer integral method. The model is expressed as two coupled ordinary differential equations that are solved numerically given a prescribed time series of free-stream velocity, horizontal pressure gradient and bore turbulence, which together represent the hydrodynamic forcing. The model was validated against two data sets of sheet flow layer thickness collected in oscillatory flow tunnels and one data set collected in the swash zone of a prototype-scale laboratory experiment. In the oscillatory flow tunnel data sets, sheet flow is mostly generated by shear stress, with pressure gradients providing an important secondary forcing around flow reversal. In the swash zone, pressure gradients and shear stresses alone are not sufficient to generate the large sheet flow layer thickness observed at the initial stages of uprush. Bore turbulence is most likely the dominant generation mechanism for this intense sheet flow.

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“…(ii) In littoral zone, the knowledge of processes benefited from the conjunction of field analyses [110,[207][208][209]217,218] and laboratory studies in oscillatory flow channels, in particular taking advantage of new methods such as the particle imaging velocimetry (PIV) [219][220][221]. A review of the progresses done from the 1980s to the 2000s was proposed by van Rijn et al [113].…”

Section: A Science Field That Evolves With Technologymentioning

confidence: 99%

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

Ouillon

2018

Water

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Scientific research on sediment dynamics in the coastal zone and along the littoral zone has evolved considerably over the last four decades. It benefits from a technological revolution that provides the community with cheaper or free tools for in situ study (e.g., sensors, gliders), remote sensing (satellite data, video cameras, drones) or modelling (open source models). These changes favour the transfer of developed methods to monitoring and management services. On the other hand, scientific research is increasingly targeted by public authorities towards finalized studies in relation to societal issues. Shoreline vulnerability is an object of concern that grows after each marine submersion or intense erosion event. Thus, during the last four decades, the production of knowledge on coastal sediment dynamics has evolved considerably, and is in tune with the needs of society. This editorial aims at synthesizing the current revolution in the scientific research related to coastal and littoral hydrosedimentary dynamics, putting into perspective connections between coasts and other geomorphological entities concerned by sediment transport, showing the links between many fragmented approaches of the topic, and introducing the papers published in the special issue of Water on "Sediment transport in coastal waters".

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Transport rate under irregular sheet flow conditions

Cited by 48 publications

References 8 publications

Sand transport under combined current and wave conditions: A semi-unsteady, practical model

Sand transport under combined current and wave conditions: A semi-unsteady, practical model

A semianalytical model for sheet flow layer thickness with application to the swash zone

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

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