Time and Bed Averaged Concentrations Under Waves

Bosman, J.J.; Steetzel, Henk J.

doi:10.1061/9780872626003.074

Cited by 6 publications

(21 citation statements)

References 3 publications

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“…with R c = ε s /w s the concentration decay length. Many field and laboratory observations (Bosman and Steetzel, 1986;Osborne and Vincent, 1996;Green and Black, 1999;Clubb, 2001;Thorne et al, 2002) show that this exponential profile describes the time-and ripple-averaged concentrations well, especially in a lower layer of 1 − 2 ripple heights where the vortex motions are dominant.…”

Section: Wave-averaged Concentrationsmentioning

confidence: 97%

“…(7.1), requires expressions for the reference concentration c 0 and the concentration decay length R c . Bosman and Steetzel (1986), Nielsen (1986), Nielsen (1990) and Lee et al (2004) proposed formulas based on extensive data sets from both field and laboratory experiments. Bosman and Steetzel (1986) performed experiments in the small oscillating water tunnel of WL|Delft Hydraulics with sinusoidal waves using sand with median grain-size D 50 = 0.22 mm.…”

Section: Introductionmentioning

confidence: 99%

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Sand Transport Over Rippled Beds in Oscillatory Flow

Werf¹,

Ribberink²

2007

Coastal Engineering 2006

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Sand Transport over Rippled Beds in Oscillatory Flow PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnificus, prof. dr. W.H.M. Zijm, volgens besluit van het College voor Promoties in het openbaar te verdedigen op vrijdag 19 mei 2006 om 15.00 uur door Jebbe Jacob van der Werf geboren op 31 oktober 1979 te Zwolle Dit proefschrift is goedgekeurd door:

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Section: Wave-averaged Concentrationsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Sand Transport Over Rippled Beds in Oscillatory Flow

Werf¹,

Ribberink²

2007

Coastal Engineering 2006

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“…The simulated concentration results generally lie between the acoustic and the optical measurements and illustrate the well-known negative exponential decay above the ripple crest (Bosman & Steetzel 1986;Nielsen 1992;Ribberink & Al-Salem 1994), of the form…”

Section: Suspended Sediment Concentrationsmentioning

confidence: 99%

Particle based modelling and simulation of natural sand dynamics in the wave bottom boundary layer

Finn

Apte

2016

J. Fluid Mech.

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Sand transport and morphological change occur in the wave bottom boundary layer due to sand particle interactions with an oscillatory flow and granular interactions between particles. Although these interactions depend strongly on the characteristics of the particle population, i.e. size and shape, little is known about how natural sand particles behave under oscillatory conditions and how variations in particle size influence transport behaviour. To enable this to be studied numerically, an Euler-Lagrange point-particle model is developed which can capture the individual and collective dynamics of subaqueous natural sand grains. Special treatments for particle collision, friction and hydrodynamic interactions are included to take into account the wide size and shape variations in natural sands. The model is used to simulate sand particle dynamics in two asymmetric oscillatory flow conditions corresponding to the vortex ripple experiments of Van der Werf et al. (J. Geophys. Res., vol. 112, 2007, F02012) and the sheet-flow experiments of O'Donoghue & Wright (Coast. Engng, vol. 50, 2004, pp. 117-138). A comparison of the phase resolved velocity and concentration fields shows overall excellent agreement between simulation and experiments. The particle based datasets are used to investigate the spatio-temporal dynamics of the particle-size distribution and the influence of three-dimensional vortical features on particle entrainment and suspension processes. For the first time, it is demonstrated that even for the relatively well-sorted medium-size sands considered here, the characteristics of the local grain size population exhibit significant space-time variation. Both conditions demonstrate a distinct coarse-over-fine armouring at the bed surface during low-velocity phases, which restricts the vertical mobility of finer fractions in the bed, and also results in strong pickup events involving disproportionately coarse fractions. The near-bed layer composition is seen to be very dynamic in the sheet-flow condition, while it remains coarse through most of the cycle in the vortex ripple condition. Particles in suspension spend more time sampling the upward directed parts of these flows, especially the smaller fractions, which delays particle settling and enhances the vertical size sorting of grains in suspension. For the submillimetre grain sizes considered, most † Email address for correspondence: J.Finn@liv.ac.uk

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“…2644. in the direction of the wave propagation as long as the opposing current was not larger than 0.2 m/s. Bosman (1982) and Bosman and Steetzel (1986) studied the effect of currents combined with waves on the suspended load transport over a sloping bed of 100 Ixm sand (nonuniform conditions). An extension of their experimental results is presented in this study, which is a part of a long-term experimental research of (fine) sand transport in combined currents and waves started in 1987 as a joint effort of Delft University of Technology and Delft Hydraulics.…”

Section: Introductionmentioning

confidence: 99%

“…Space averaging over length L must be applied to eliminate the strong influence of the bed forms on the local variables (Bosman and Steetzel 1986 …”

Section: Introductionmentioning

confidence: 99%

Transport of Fine Sands by Currents and Waves

Rijn¹,

Nieuwjaar

Kaay

et al. 1993

J. Waterway, Port, Coastal, Ocean Eng.

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ABSTRACT:The transport process of fine sands in combined current and wave conditions in a flume was studied. Two types of sediment material were used, a very fine sand with a median diameter of about 100 ~m and a medium-fine sand with a diameter of 200 txm. The current velocities were varied in the range of 0.1-0.5 m/s (following and opposing the waves). Irregular waves with a single-topped spectrum and peak period of 2.5 s were generated. The significant wave height varied in the range of 0.075 m to 0.18 m. The water depth was about 0.5 m in all tests. Time-averaged fluid velocities were measured by an electromagnetic current meter. Time-averaged sediment concentrations were measured by a pump sampler. The transport rate was obtained by integration of the product of velocity and concentration over the depth. The generation of waves in following or opposing currents causes a decrease of the time-averaged velocities in the near-bed region. A larger wave height results in larger concentrations and in a more uniform distribution over the depth. The influence of the current direction on the concentration profile and the transport rate is negligible.

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Time and Bed Averaged Concentrations Under Waves

Cited by 6 publications

References 3 publications

Sand Transport Over Rippled Beds in Oscillatory Flow

Sand Transport Over Rippled Beds in Oscillatory Flow

Particle based modelling and simulation of natural sand dynamics in the wave bottom boundary layer

Transport of Fine Sands by Currents and Waves

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