Video-derived near bed and sheet flow sediment particle velocities in dam-break-driven swash

Puleo, Jack A.; Krafft, Douglas; Pintado-Patiño, José Carlos; Bruder, Brittany

doi:10.1016/j.coastaleng.2017.04.008

Cited by 12 publications

(7 citation statements)

References 36 publications

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“…The shape of the profile within the mobile bed layer was governed by the profile shape parameter, α , in , where α = 0.50 was used. Prior studies that measured the velocity profile in the mobile bed layer have observed values for α between 0.25 and 1.0 (Puleo et al, ; Sumer et al, ; Wang & Yu, ; Zala Flores & Sleath, ). Studies that require the velocity profile in the mobile bed layer to be approximated tend to assume a linear velocity profile (i.e., α = 1.0; O'Donoghue & Wright, ; Puleo et al, ; Zala Flores & Sleath, ).…”

Section: Discussionmentioning

confidence: 99%

“…Velocity profiles in the mobile bed layer for each ensemble, [ u bl ( t / T , z * )] n , were approximated by extrapolating the measured velocity at the top of the mobile bed,

{[u (t / T, z^{*} = z_{top}^{*})]}_{n}

, down to zero velocity at the bottom of the mobile bed layer (Pugh & Wilson, ; Sumer et al, ; Wang & Yu, ),

{[u^{normalbl} (t / T, z^{*})]}_{n} = {[u (t / T, z^{*} = z_{top}^{*})]}_{n} {(\frac{z^{*} - z_{bott}^{*}}{z_{top}^{*} - z_{bott}^{*}})}_{n}^{α},

where the exponent, α , is a profile shape parameter (0 < α ≤ 1), with α = 1 yielding a linearly decreasing profile through the mobile bed layer. A square‐root‐shaped velocity profile, α = 0.50 (Puleo et al, ; Wang & Yu, ), was used to estimate the velocity profile in the mobile bed layer for each time step (Mieras et al, ). The sensitivity of net bed load transport rates to the profile shape parameter is explored further in section .…”

Section: Data Treatmentmentioning

confidence: 99%

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Relative Contributions of Bed Load and Suspended Load to Sediment Transport Under Skewed‐Asymmetric Waves on a Sandbar Crest

et al. 2019

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A large‐scale laboratory experiment was conducted to evaluate cross‐shore sediment transport and bed response on a sandbar under erosive and accretive field‐scale wave conditions (total of 11 cases). Unprecedented vertical resolution of sediment concentration was achieved through the use of conductivity concentration profilers alongside miniature fiber optic backscatter profilers. Observations were made of intrawave (phase‐averaged) and wave‐averaged cross‐shore sediment flux profiles and transport rates in the lower half of the water column on the crest of a sandbar. The net sediment transport rate was partitioned into suspended sediment (SS) and bed load (BL) components to quantify the relative contributions of SS and BL to the total sediment transport rate. Net SS transport rates were greater than net BL transport rates for the positive (wave crest) half‐cycle in 6 of 11 cases, compared to 100% (11 of 11) for the negative (wave trough) half‐cycle. Net (wave‐averaged) BL transport rates were greater, in magnitude, than net SS transport rates for 7 of the 11 cases. The dominant mode of transport was determined from the ratio of net BL to net SS transport rate magnitudes. The net transport rate was negative (offshore‐directed) when SS dominated and positive (onshore‐directed) when BL dominated. Net BL transport rate correlated well with third moments of free‐stream velocity (r2 = 0.72), suggesting that energetics‐type quasi‐steady formulae may be suitable for predicting BL transport under the range of test conditions.

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Section: Discussionmentioning

confidence: 99%

“…Velocity profiles in the mobile bed layer for each ensemble, [ u bl ( t / T , z * )] n , were approximated by extrapolating the measured velocity at the top of the mobile bed,

{[u (t / T, z^{*} = z_{top}^{*})]}_{n}

, down to zero velocity at the bottom of the mobile bed layer (Pugh & Wilson, ; Sumer et al, ; Wang & Yu, ),

{[u^{normalbl} (t / T, z^{*})]}_{n} = {[u (t / T, z^{*} = z_{top}^{*})]}_{n} {(\frac{z^{*} - z_{bott}^{*}}{z_{top}^{*} - z_{bott}^{*}})}_{n}^{α},

Section: Data Treatmentmentioning

confidence: 99%

Relative Contributions of Bed Load and Suspended Load to Sediment Transport Under Skewed‐Asymmetric Waves on a Sandbar Crest

et al. 2019

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“…where u p (δ s ) is the particle velocity at the top of the sheet flow layer; n is an empirical shape factor. Values proposed for n are in the range of 0.5 to 1 (Wilson, 1966;Sumer et al, 1996;Wang and Yu, 2007;Puleo et al, 2016Puleo et al, , 2017; n = 0.75 following Sumer et al (1996) was adopted in the present study. The particle velocity at the top of the sheet flow layer was directly measured by the CCM + .…”

Section: Particle Velocitiesmentioning

confidence: 99%

Sand transport processes and bed level changes induced by two alternating laboratory swash events

Zanden

Caceres

Eichentopf

et al. 2019

Coastal Engineering

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Sand transport processes and net transport rates are studied in a largescale laboratory swash zone. Bichromatic waves with a phase modulation were generated, producing two continuously alternating swash events that have similar offshore wave statistics but which differ in terms of wave-swash interactions. Measured sand suspension and sheet flow dynamics show strong temporal and spatial variability, related to variations in flow velocity and locations of wave capture and wave-backwash interactions. Suspended and sheet flow layer transport rates in the lower swash zone are generally of same magnitude, but sheet flow exceeds the suspended load transport by up to a factor four during the early uprush. The bed level near the inner surf zone is relatively steady during a swash cycle, but changes of O(cm/s) are measured near the mid swash zone where wave-swash interactions lead

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“…Sheet flow velocity profiles were related to the flow field adjacent to the top layer of sheet flow (Equation B3, Appendix B5). The exponent, k = 0.62, was initially suggested for sediment particle velocity profiles in the swash zone (Puleo et al., 2017), and k = 0.75–1.0 was applied to compute sheet layer velocities in uniform and oscillatory flow (Sumer et al., 1996; Wilson, 1966). An exponent, k = 0.5, was selected to evaluate inner‐surf and swash zone sheet flows in this study.…”

Section: Discussionmentioning

confidence: 99%

“…where u s is the fluid velocity in the sheet layer and u δs is the fluid velocity 1 mm above the top of the sheet layer. k is an empirical exponent that was set equal to 0.5 (Puleo et al, 2017;Y. H. Wang & Yu, 2007;Wilson, 1966), and δ s is the sheet layer thickness defined as the vertical distance between the bottom and top boundary of the sheet layer, δ s = z* − z′.…”

Section: B5 Velocities In the Sheet Layermentioning

confidence: 99%

Geomorphic Response of a Coastal Berm to Storm Surge and the Importance of Sheet Flow Dynamics

Pontiki,

Puleo,

Bond

et al. 2023

JGR Earth Surface

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During a storm, as the beach profile is impacted by increased wave forcing and rapidly changing water levels, sand berms may help mitigate erosion of the backshore. Yet, the mechanics of berm morphodynamics have not been fully described. In this study, twenty‐six trials were conducted in a large wave flume to explore the response of a near‐prototype berm to scaled storm conditions. Sensors were used to quantify hydrodynamics, sheet flow dynamics, and berm evolution. Results indicate that berm overtopping, and offshore sediment transport were key processes causing berm erosion. During the morphological evolution of the beach profile, two sand bars were formed offshore that attenuated subsequent wave energy. The landward extent of that energy was confined to the seaward foreshore inhibiting inundation of the backshore. Net offshore‐directed transport was dominant when infragravity motions increased in the swash zone. Conversely, the influence of incident‐band motions on sediment transport was relatively greater in the inner‐surf zone. Near‐bed flow velocities and sheet flow layer thicknesses were larger in the swash zone than in the inner‐surf zone. This paper also provides a valuable analysis between morphology‐estimated total sediment transport rates and rates derived from in situ measurements. Sheet flow dynamics dominated foreshore cross‐shore sediment processes constituting the largest portion of the total sediment transport load throughout the berm erosion.

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Video-derived near bed and sheet flow sediment particle velocities in dam-break-driven swash

Cited by 12 publications

References 36 publications

Relative Contributions of Bed Load and Suspended Load to Sediment Transport Under Skewed‐Asymmetric Waves on a Sandbar Crest

Relative Contributions of Bed Load and Suspended Load to Sediment Transport Under Skewed‐Asymmetric Waves on a Sandbar Crest

Sand transport processes and bed level changes induced by two alternating laboratory swash events

Geomorphic Response of a Coastal Berm to Storm Surge and the Importance of Sheet Flow Dynamics

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