Abreu

B. G. Ruessink

Betteridge

Bosman

Calantoni

D. A. Van der A

Davies

Dibajnia

Dick

Doering

Dohmen-Janssen

Dong

Drake

Elfrink

Elgar

F. Sancho

Foster

Gonzalez-Rodriguez

H. Michallet

Hassan

Hurther

J. J. Van der Werf

King

Lentz

Longuet-Higgins

Malarkey

McLean

Nadaoka

Nielsen

O'Donoghue

P. A. Silva

Reniers

Ribberink

Roelvink

Ruessink

Schretlen

Scott

Silva

Sleath

Suntoyo

Svendsen

T. Abreu

Thorne

Van der A

Watanabe

Journal of Geophysical Research Atmospheres

English

Ruessink, B. Gerben

Michallet, Hervé

Abreu, Tiago

Sancho, Francisco

van Der A, Dominic A.

van Der Werf, Jebbe J.

Silva, Paulo A.

HAL: Hyper Article en Ligne

Observations of velocities, sand concentrations, and fluxes under velocity‐asymmetric oscillatory flows

U-tube measurements of instantaneous velocities, concentrations, and fluxes for a well-sorted, medium-sized sand in oscillatory sheet flow are analyzed. The experiments involved two velocity-asymmetric flows, the same two flows with an opposing current of 0.4 m/s, and a mixed skewed-asymmetric flow, all with a velocity amplitude of 1.2 m/s and flow period of 7 s. We find that the net positive transport rate beneath velocity-asymmetric oscillatory flow results from large, but opposing sand fluxes during the positive and negative flow phase. With an increase in velocity asymmetry and, in particular, velocity skewness, the difference in the magnitude of the fluxes in the two half cycles increases, leading to larger net transport rates. This trend is consistent with the observed increase in skewness of the oscillatory bed shear stress. Phase-lag effects, whereby sand stirred during the negative flow phase has not settled by the time of the negative-to-positive flow reversal and is subsequently transported during the positive flow phase, are notable but of minor importance to the net transport rate compared to earlier experiments with finer sands. In the vertical, the oscillatory flux is positive above the no-flow bed. Within the sheet flow pick-up layer, the oscillatory flux is negative and similar in magnitude to the positive flux induced by the residual flow. The 0.4 m/s opposing current causes more sand to be picked up during the negative than during the positive flow phase. Above the no-flow bed the resulting negative oscillatory flux is comparable in magnitude to the current-related flux

Ruessink, B.G.

Michallet, H.

Abreu, T.

Sancho, F.

van der A, D.A.

van der Werf, J.J.

Silva, P.A.

University of Twente Research Information

Observations of velocities, sand concentrations, and fluxes under velocity-asymmetric oscillatory flows

A, D.A. van der

Werf, J.J. van der

Utrecht University Repository

U‐tube measurements of instantaneous velocities, concentrations, and fluxes for a well‐sorted, medium‐sized sand in oscillatory sheet flow are analyzed. The experiments involved two velocity‐asymmetric flows, the same two flows with an opposing current of 0.4 m/s, and a mixed skewed‐asymmetric flow, all with a velocity amplitude of 1.2 m/s and flow period of 7 s. We find that the net positive transport rate beneath velocityasymmetric oscillatory flow results from large, but opposing sand fluxes during the positive and negative flow phase. With an increase in velocity asymmetry and, in particular, velocity skewness, the difference in the magnitude of the fluxes in the two half cycles increases, leading to larger net transport rates. This trend is consistent with the observed increase in skewness of the oscillatory bed shear stress. Phase‐lag effects, whereby sand stirred during the negative flow phase has not settled by the time of the negative‐to‐positive flow reversal and is subsequently transported during the positive flow phase, are notable but of minor importance to the net transport rate compared to earlier experiments with finer sands. In the vertical, the oscillatory flux is positive above the noflow bed. Within the sheet flow pick‐up layer, the oscillatory flux is negative and similar in magnitude to the positive flux induced by the residual flow. The 0.4 m/s opposing current causes more sand to be picked up during the negative than during the positive flow phase. Above the no‐flow bed the resulting negative oscillatory flux is comparable in magnitude to the current‐related flux.The work presented here was part of the TRANSKEW project supported by the European Community’s Sixth Framework Programme through the grant to the budget of the Integrated Infrastructure Initiative HYDRALAB III, contract 022441 (RII3). B.G.R. acknowledges additional funding by the Netherlands Organisation for Scientific Research NWO under project 864.04.007. We thank André Temperville, Tom O’Donoghue, Jan Ribberink, Paula Freire, Sandra Plecha, Kate Steenhauer, Gustaaf Kikkert, John Cornelisse, and Noureddine Ait Lafkih for their help and technical support during the experiments. Supported by the HYDRALAB III project SANDS, Maarten Kleinhans assisted with the inversion of the ABS voltage to sand concentration and David Hurther developed the hardware and software used to process the ADVP data. Useful and constructive comments from three anonymous reviewers helped improve the manuscript.publishe

Ruessink, B. G.

Van Der A, D. A.

Van Der Werf, J. J.

Silva, P. A.

Repositório Institucional da Universidade de Aveiro

Journal of Geophysical Research Oceans

Crossref

NARCIS 

(2004a), Concentrations in oscillatory sheet flow for well sorted and graded sands,

A correction method for turbulence measurements with a 3D acoustic Doppler velocity profiler,

A review of acoustic measurement of small‐scale sediment processes,

A sheet‐flow transport rate formulations for asymmetric, forward‐leaning waves and currents,

Acoustic measurements of suspended sediments in turbulent currents and comparison with in‐situ samples,

Al‐Salem

Analysis of surf zone turbulence,

Analytical approximate wave form for asymmetric waves,

Calibrating multi‐frequency acoustic backscatter systems for studying near‐bed suspended sediment transport processes,

Characteristics of turbulent boundary layers over a rough bed under saw‐tooth waves and its application to sediment transport,

Coastal Bottom Boundary Layers and Sediment Transport, 324 pp., World Sci.,

Conditions for plug formation in oscillatory flow,

Constraining acoustic backscatter estimates of suspended sediment concentration profiles using the bed echo,

Discrete particle model for sheet flow sediment transport in the nearshore,

Estimation of sediment particle velocities in the sheet flow: Cross‐correlation and wavelet analysis,

Field evidence of pressure gradient induced incipient motion,

Flow tunnel measurements of velocities and sand flux in oscillatory sheet flow for well‐sorted and graded sands,

Hanes (2004), Effects of wave shape on sheet flow sediment transport,

Identification of intense, intermittent coherent motions under shoaling and breaking waves,

Intense near‐bed sediment motions in waves and currents,

Intrawave measurements of suspended sediment concentrations: the TRANSKEW ABS data report,

M a l a r k e y ,J .

Mass transport in water waves,

Modeling sediment transport beneath skewed asymmetric waves above a plane bed,

Modelling sediment transport beneath regular symmetrical and asymmetrical waves above a plane bed,

Observations and a model of undertow over the inner continental shelf,

Observations of bispectra of shoaling surface gravity waves,

Observations of turbulence within a natural surf zone,

Parameterization and simulation of near bed orbital velocities under irregular waves in shallow water,

Parameterization of orbital velocity asymmetries of shoaling and breaking waves using bispectral analysis,

Ribberink (2002), Phase lags in oscillatory sheet flow: Experiments and bed load modelling,

Ribberink (2005), Transport processes of uniform and mixed sands in oscillatory sheet flow,

Ribberink (2008), Effects of acceleration skewness on rough bed oscillatory boundary layer flow,

Ribberink (2010), Measurements of sheet flow transport in acceleration‐skewed oscillatory flow and comparison with practical formulations,

Role of pressure gradients in sheet flow of coarse sediments under sawtooth waves,

Sand motion induced by oscillatory flows: Sheet flow and vortex ripples,

Sand transport in oscillatory sheet flow with mean current,

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

Sand transport under full‐scale surface waves, paper 123

Seabed shear stress and bedload transport due to asymmetric and skewed waves,

Sediment concentration measurement by transverse suction,

Sediment suspension due to large scale eddies in the surf zone,

Sediment transport in oscillatory sheet flow,

Sheet flow dynamics under monochromatic non‐breaking waves,

Sheet flow sand transport processes in oscillatory flow with acceleration skewness, paper 133

Sheet flow sediment transport under waves with acceleration skewness and boundary layer streaming,

Steep wave, turbulence, and sediment concentration statistics beneath a breaking wave field and their implications for sediment transport,

Stive

Structure of the turbulent flow field under breaking waves in the surf zone,

Studies in oscillatory flow bedload sediment transport,

Transport rate under irregular sheet flow conditions,

Observations of velocities, sand concentrations, and fluxes under velocity-asymmetric oscillatory flows

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