Spatial variability of the wave bottom boundary layer over movable rippled beds

Rodriguez-Abudo, S.; Foster, D. L.; Henriquez, Martijn

doi:10.1002/jgrc.20256

Cited by 18 publications

(23 citation statements)

References 76 publications

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“…The time between image pair members (

Δ t =

4‐10 ms) was chosen based on the hydrodynamics of each data set (Table ), and resulting velocity vectors calculated using MatPIV 1.6.1 [ Sveen , ]. An Acoustic Doppler Velocimeter (ADV), time‐synchronized with the PIV system, validated the velocity vectors outside the boundary layer [ Nichols and Foster , ; Rodriguez‐Abudo et al ., ]. Additional information on the PIV processing and postprocessing techniques, spatial resolution, uncertainty levels, and settling bias, can be found in Rodriguez‐Abudo et al .…”

Section: Observationsmentioning

confidence: 99%

“…Additional information on the PIV processing and postprocessing techniques, spatial resolution, uncertainty levels, and settling bias, can be found in Rodriguez‐Abudo et al . [].…”

Section: Observationsmentioning

confidence: 99%

“…Following Rodriguez‐Abudo et al . [], bed elevation estimates (

z_{b e d} (x, \overset{t}{true})

) were computed from the mean and maximum pixel intensity over the wave phase

\tilde{t}

. A baseline for the estimate (

z_{b a s e} (x, \overset{t}{true})

) was computed from the maximum pixel image by identifying the lowest elevation of saturated pixels for each individual x .…”

Section: Observationsmentioning

confidence: 99%

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Direct estimates of friction factors for a mobile rippled bed

Rodriguez-Abudo

Foster

2017

JGR Oceans

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New friction factor estimates are computed from the total momentum transfer applied to a rippled sediment bed. The total time‐dependent momentum flux is achieved by implementing the double‐averaged horizontal momentum equation on the nearbed flow field collected with PIV. Time‐independent friction factors are obtained by regressing the total momentum flux to the common quadratic stress law given by 12ρu∞|u∞|. The resulting friction factors compare favorably with available analysis techniques including energy dissipation, vertical turbulence intensity, and maximum shear stress, but can be 2‐6 times smaller than estimates determined with the model by Madsen (1994) and the formula of Swart (1974) using the ripple roughness.

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“…The time between image pair members (

Δ t =

Section: Observationsmentioning

confidence: 99%

“…Additional information on the PIV processing and postprocessing techniques, spatial resolution, uncertainty levels, and settling bias, can be found in Rodriguez‐Abudo et al . [].…”

Section: Observationsmentioning

confidence: 99%

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Direct estimates of friction factors for a mobile rippled bed

Rodriguez-Abudo

Foster

2017

JGR Oceans

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“…Laboratory measurements of velocity obtained from particle image velocimetry (PIV) were used to compute phase averaged velocity, vorticity, and swirling strength through a vertical slice in the water column (Rodriguez-Abudo and Foster, 2010;Rodriguez-Abudo and Foster, in prep). Measured velocity time series from a laboratory ADV (acoustic doppler velocimeter) located outside the wave bottom boundary layer was used to drive simulations.…”

Section: Work Completedmentioning

confidence: 99%

Massively Scalable Mixture Model for Small-scale Sand Ripples

Calantoni

Penko

2011

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Award Number: N0001410WX20018 http://www7400.nrlssc.navy.mil/index.htm LONG-TERM GOALSOur long-term goal is to develop a modeling framework to predict sediment transport, the evolution of seafloor roughness, and acoustic propagation through the seafloor in the nearshore and littoral battlespace environment. OBJECTIVESOur primary objective is to develop and validate a massively parallel version of an existing mixture model, SedMix3D (Penko et al., in press), for simulating small-scale ripple dynamics in shallow littoral environments. Applicability of the serial version of SedMix3D is severely hampered by physical limitations (memory and CPU speed) of typical desktop workstations. The scalable version of SedMix3D developed here will be able to simulate prototype size domains as found in the center of a laboratory U-tube (up to 1 m in length), for example. The parallel version of SedMix3D is a powerful research tool that will be used to study the details of small-scale sand ripple dynamics including (1) the effects of suspended sediment concentration on turbulence modulation, (2) the dynamics of ripple transitions from 2D to 3D (and back to 2D) under changing forcing conditions, and (3) the role of terminations and bifurcations on ripple migration and growth rates. APPROACHSedMix3D solves the unfiltered Navier-Stokes equations for the fluid-sediment mixture with the addition of a sediment flux equation that considers the balance between gravitational settling, advection, and diffusion. The capability of SedMix3D to simulate small-scale sand ripple dynamics has been illustrated both qualitatively and quantitatively (Penko and Slinn, 2006;Penko et al., 2008;

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“…The observations were made in a wave flume at the Fluid Mechanics Laboratory at Delft University of Technology, Netherlands using a particle image velocimetry technique [6]. The wave flume is 42 m in length, 0.8 m in width, and 1 m in height, with the bottom covered with a layer of sediment.…”

Section: Experimental Set-upmentioning

confidence: 99%

Three-dimensional mixture theory simulations of turbulent flow over dynamic rippled beds

Penko¹,

Calantoni²

2012

Advances in Fluid Mechanics IX

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The highly turbulent, sediment-laden flow above rippled beds in the wave bottom boundary layer (WBBL) is poorly understood and difficult to quantify mainly because of our failure to understand the fundamental interaction forces driving sediment transport. However, recent advances in high performance computing allow for highly resolved simulations of fluid-sediment dynamics in the WBBL to examine the small-scale fluctuations of boundary layer processes and characterize seabed morphology. A three-dimensional mixture theory model, SedMix3D, solves the unfiltered Navier-Stokes equations for the fluid-sediment mixture with an additional equation describing sediment flux. Mixture theory treats the fluid-sediment mixture as a single continuum with effective properties parameterizing the intra-and inter-phase interactions with closure relations for the mixture viscosity, diffusion, hindered settling, and particle pressure. We validate results obtained with SedMix3D using temporally and spatially resolved fluid velocity measurements acquired with a particle image velocimetry (PIV) system in a free-surface laboratory flume. Measured two-dimensional velocity fields are compared to two-dimensional vertical slices from the threedimensional simulation domain. We examine the hydrodynamics of the flow by comparing bulk flow statistics, and swirling strength. In general, results from SedMix3D were in excellent agreement with the observations. We believe SedMix3D captures the essential physics governing two-phase turbulent flow over ripples for the conditions represented by the experiments and should provide us with a powerful research tool for studying the dynamics of seafloor bedforms.

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Spatial variability of the wave bottom boundary layer over movable rippled beds

Cited by 18 publications

References 76 publications

Direct estimates of friction factors for a mobile rippled bed

Direct estimates of friction factors for a mobile rippled bed

Massively Scalable Mixture Model for Small-scale Sand Ripples

Three-dimensional mixture theory simulations of turbulent flow over dynamic rippled beds

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