Estimation of the velocity field induced by plunging breakers in the surf and swash zones

Rivillas-Ospina, Germán; Acuña, Adrián Pedrozo; Silva, Rodolfo; Torres-Freyermuth, Alec; Gutierrez, César

doi:10.1007/s00348-011-1208-x

Cited by 18 publications

(12 citation statements)

References 45 publications

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“…Petti and Longo, 2001;Cowen et al, 2003;Gedik et al, 2005;Shin and Cox, 2006;Sou et al, 2010;Rivillas-Ospina et al, 2012). Large-scale wave flume experiments have studied sand suspension processes in the swash zone Caceres and Alsina, 2012), interactions between surf and swash bed dynamics , the effects of 2 long waves, wave groups and random waves on surf and swash bed dynamics (Baldock et al, 2011) and beach groundwater effects on swash sediment transport (Masselink and Turner, 2012) The complexity of processes at work in the field and in large-scale wave flume experiments makes it difficult to isolate and quantify fundamental processes and to provide measurements of the kind needed for the development of swash numerical models.…”

Section: Introductionmentioning

confidence: 99%

Intra-swash hydrodynamics and sediment flux for dambreak swash on coarse-grained beaches

O’Donoghue

Kikkert

Pokrajac

et al. 2016

Coastal Engineering

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The paper reports on dambreak-type swash experiments in which intra-swash hydrodynamics and sediment flux are measured for swash on a coarse sand beach and a gravel beach. Flow velocity and depth are measured using PIV and LIF respectively; the intra-swash sediment flux is measured using sediment traps. Comparison of measured hydrodynamics with the immobile, permeable bed experiments of Kikkert et al. (2013) indicate that bed mobility impacts on the swash hydrodynamics, reducing the maximum run-up by approximately 8% for both beaches, compared to the maximum run-up on the corresponding immobile beach. The measured intra swash sediment flux at a given location is characterised by high flux at the moment of bore arrival, followed by rapid decay during uprush, becoming zero at some time before flow reversal. For the gravel beach, the backwash sediment flux is negligibly small, while for the sand beach the backwash flux increases slowly as the flow accelerates down the beach, and peaks at about the time of maximum backwash velocity. Intraswash sediment flux calculated using the Meyer-Peter and Müller bed load transport formula, with measured hydrodynamics as input and bed shear stress estimated using both the Swart and Colebrook formulae, are within a factor 2 of the measured intra-swash flux. The agreement between the calculated and measured flux is better for the sand beach than for the gravel beach, and better for uprush than for backwash. For the sand beach there is good agreement between calculated and measured total uprush and total backwash sediment volumes. The agreement is less good for the gravel beach, for which calculated and measured uprush volumes show a similar trend but the calculated backwash volumes over-estimate the (negligible) volumes observed in the experiments. Field experiments investigating swash hydrodynamics and sediment dynamics have developed substantially over the last two decades in terms of the sophistication of the instruments deployed and the degree to which detailed processes are captured by the measurements. Regarding sediment flux, sediment trapping has been used to measure total uprush and total backwash transport volumes (Hughes et al., 1997;Masselink and Hughes, 1998;Austin & Masselink, 2006;Masselink et al., 2009) and high-resolution bed elevation measurements across the swash zone have been used to obtain net sediment transport volumes for individual swash events (e.g. Blenkinsopp et al., 2011). These measurements are extremely valuable in terms of quantifying sediment fluxes and morphological change for swash events in the field. However, they do not provide a complete picture since they reveal little (in the case of traps) or nothing (in the case of bed elevation measurements) of the sediment flux during a swash event. In principle, measurements of intra-swash sediment flux can be obtained from co-located measurements of velocities and concentrations, but obtaining these measurements sufficiently accurately over the complete water column to give total sediment flux...

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Section: Introductionmentioning

confidence: 99%

Intra-swash hydrodynamics and sediment flux for dambreak swash on coarse-grained beaches

O’Donoghue

Kikkert

Pokrajac

et al. 2016

Coastal Engineering

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“…Therefore, non-intrusive techniques have been employed to measure the flow properties in aerated flows, such Particle Image Velocimetry (PIV). This technique was successfully applied for the measurements of flow fields in the surf zone (Govender et al 2004), which is the base of this work and is the continuation of previous research in the analysis of wave propagation under plunging breakers (Rivillas et al 2011) that shows an investigation into the spatial and temporal evolution of the velocity field induced by plunging waves using the Bubble Image Velocimetry (BIV) technique.…”

Section: Introductionmentioning

confidence: 94%

Integrated Study on the Velocity Field Induced by Plunging Breakers

Rivillas¹,

Acuña²,

Silva³

et al. 2012

Int. Conf. Coastal. Eng.

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In this investigation we employ a technique called Bubble Image Velocimeter (BIV) to obtain measurements of flow fields in the surf-zone. This technique allows measurements of flow velocity in the aerated breaking zone, where other techniques are ineffective. The technique has been widely used to study flow propagation in front of vertical structures, it is employed in this study to estimate the velocity field induced by the propagation of a plunging wave travelling over an impermeable slope. The BIV measurements were compared to those obtained with an Acoustic Doppler Velocimeter (ADV) showing that the BIV technique is more suitable when the velocity field is estimated under the presence of an aerated flow. Moreover, the phase-averaged velocity fields obtained from the numerical model were compared against those evaluated from the BIV measurements. A reliable estimation of the VOF-type numerical derivations in the surf zone was established. In the swash zone, an over prediction of the offshore flow was identified.

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“…The technique works by comparing the textural change between consecutive video images. BIV experiments include: run-up and green water velocities due to breaking wave impinging and overtopping (Ryu, Chang, & Mercier, 2007); the estimation of velocity components in a turbulent bore in small-scale wave-structure interaction experiments (Antoine, 2009) and plunging breakers in the surf zone (Rivillas-Ospina, Pedrozo-Acuna, Silva, Torres-Freyermuth, & Gutierrez, 2012).…”

Section: Literaturementioning

confidence: 99%

Individual violent wave-overtopping events: behaviour and estimation

Raby

Jayaratne

Bredmose³

et al. 2019

Journal of Hydraulic Research

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To better understand individual violent wave overtopping, of significance for coastal defence design, three breaking wave types (steep-fronted, plunging and broken) based on focused wave groups, were generated in laboratory and numerical models. High-speed video captured overtopping events and produced velocity vector maps by means of bubble image velocimetry (BIV). Results were compared with a numerical model based on a linear wave detection procedure and a two-phase incompressible Navier-Stokes-based solver. This novel approach revealed that the overtopping waves comprised an initial jet of 0.2 s duration, but dominated by quasi-steady flow. Whilst laboratory surface-elevation time-histories were highly repeatable, overtopping volume repeats were sensitive to the breaker type. Measured volumes were compared with: the numerical model (which over-predicted, but was reasonably accurate for steep-fronted waves); estimations based on BIV results (which provided very close agreement for the steep-fronted waves); and a weir-based analogy (which provided reasonable agreement, but always under-predicted).

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Estimation of the velocity field induced by plunging breakers in the surf and swash zones

Cited by 18 publications

References 45 publications

Intra-swash hydrodynamics and sediment flux for dambreak swash on coarse-grained beaches

Intra-swash hydrodynamics and sediment flux for dambreak swash on coarse-grained beaches

Integrated Study on the Velocity Field Induced by Plunging Breakers

Individual violent wave-overtopping events: behaviour and estimation

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