Near bed cross-shore velocity profiles, bed shear stress and friction on the foreshore of a microtidal beach

Puleo, Jack A.; Lanckriet, Thijs; Wang, Ping

doi:10.1016/j.coastaleng.2012.04.007

Cited by 42 publications

(60 citation statements)

References 37 publications

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“…Estimates of the flow velocity were also unavailable. Log-law fitting over loose beds in the field (Masselink et al, 2005;Puleo et al, 2012) suggests that stresses are greater in the uprush than in the backwash, consistent with fixed bed data from shear plates and the log-law (Kikkert et al, 2012(Kikkert et al, , 2013O'Donoghue et al, 2010). However, in the field case, no direct comparison between fixed and loose beds is possible.…”

Section: Introductionsupporting

confidence: 70%

“…This is true for both LDA and PIV instruments (Cowen et al, 2003), as well as ultrasonic instruments (ADV and ADVP, Allis et al, 2014;O'Donoghue et al, 2010;Puleo et al, 2012), even at large experimental scales. For example, in recent experiments in the GWK at Forschungszentrum Küste (FZK) in Hannover, Germany, with monochromatic wave of T = 8 s and H = 0.9 m, ADV and ADVP instruments could not yield data until after 1.6 s after the wave front passed the measurement location (Allis et al, 2014).…”

Section: Hydrodynamic Modellingmentioning

confidence: 80%

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Direct bed shear measurements under loose bed swash flows

Zhu

Baldock

2015

Coastal Engineering

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Section: Introductionsupporting

confidence: 70%

Section: Hydrodynamic Modellingmentioning

confidence: 80%

Direct bed shear measurements under loose bed swash flows

Zhu

Baldock

2015

Coastal Engineering

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“…However, laboratory based studies of swash flows over fixed beds have concluded that the log law does not predict adequately the leading and trailing edges of the bore front [Barnes et al, 2009], and the near flow reversal phases [Cox et al, 2001;Archetti and Brocchini, 2002;O'Donoghue et al, 2010;Kikkert et al, 2012]. Thus, the suitability of this assumption under natural settings may be limited to certain flow conditions [Puleo et al, 2012[Puleo et al, , 2014a as confirmed by field measurements of near bed velocity profiles at a highresolution (100 Hz at 1 mm vertical spacing).…”

Section: Introductionmentioning

confidence: 97%

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

et al. 2015

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Boundary layer dynamics are investigated using a 2‐D numerical model that solves the Volume‐Averaged Reynolds‐Averaged Navier‐Stokes equations, with a VOF‐tracking scheme and a k ‐ ϵ turbulence closure. The model is validated with highly resolved data of dam break driven swash flows over gravel impermeable and permeable beds. The spatial gradients of the velocity, bed shear stress, and turbulence intensity terms are investigated with reference to bottom boundary layer (BL) dynamics. Numerical results show that the mean vorticity responds to flow divergence/convergence at the surface that result from accelerating/decelerating portions of the flow, bed shear stress, and sinking/injection of turbulence due to infiltration/exfiltration. Hence, the zero up‐crossing of the vorticity is employed as a proxy of the BL thickness inside the shallow swash zone flows. During the uprush phase, the BL develops almost instantaneously with bore arrival and fluctuates below the surface due to flow instabilities and related horizontal straining. In contrast, during the backwash phase, the BL grows quasi‐linearly with less influence of surface‐induced forces. However, the infiltration produces a reduction of the maximum excursion and duration of the swash event. These effects have important implications for the BL development. The numerical results suggest that the BL growth rate deviates rapidly from a quasi‐linear trend if the infiltration is dominant during the initial backwash phase and the flat plate boundary layer theory may no longer be applicable under these conditions.

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“…Laser Doppler Anemometry (LDA), Particle Image Velocimetry (PIV, e.g. Cowen et al, 2003), Acoustic Doppler Velocimetry (ADV, O'Donoghue et al, 2010) or Acoustic Doppler Velocity Profiler (ADVP, Puleo et al,2012;Allis et al, 2014). However, challenges still exist.…”

Section: Introductionmentioning

confidence: 99%

Bed Shear Stress Meaurements Over Rough Fixed and Mobile Sediment Beds in Swash Flows

Zhu

Baldock

2014

Int. Conf. Coastal. Eng.

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Direct measurements of bed shear stress have been conducted over rough fixed and mobile sediment beds in dambreak driven swash flows. The comparison between rough fixed and mobile bed results indicated the significant importance of grain borne shear stress component, induced by increased dispersive stress and the momentum transfer by moving sediment grains to the bed. The increase of the averaged peak bed shear stress under mobile sediment beds can be up to 100% of that for fixed beds. The direct incorporation of the shear stress data into the classic MeyerPeter&Muller (1948) bed load model leads to over-estimate of bed load transport rate and reveals the fact of starved bed conditions applied in the present experiments.

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Near bed cross-shore velocity profiles, bed shear stress and friction on the foreshore of a microtidal beach

Cited by 42 publications

References 37 publications

Direct bed shear measurements under loose bed swash flows

Direct bed shear measurements under loose bed swash flows

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

Bed Shear Stress Meaurements Over Rough Fixed and Mobile Sediment Beds in Swash Flows

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