Initial motion of sediment under waves and wave-current combined motions

Tanaka, Hitoshi; To, D. V.

doi:10.1016/0378-3839(94)00047-2

Cited by 14 publications

(8 citation statements)

References 9 publications

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“…Tanaka and Van To (1995) collected some experimental data for oscillatory conditions and the results showed that most of the data fall within the laminar-transitional-rough turbulent region.…”

Section: Analysis Of Sediment Incipient Motion Under Waves Andmentioning

confidence: 99%

“…Some scholars, e.g., Dou (2000) and Eagleson et al (1957) established formulas by combining flume experimental data with theoretical analysis. The Shields curve was extended to wave conditions by some scholars (Madsen and Grant, 1976;Soulsby and Whitehouse, 1997;Tanaka and Van To, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…The first one is the Shields curve. Experiments and theoretical studies proved that the Shields curve could also be used in wave and wave-current conditions (Li, 2014;Madsen and Grant, 1976;Tanaka and Van To, 1995;Willis, 1978;Zhou et al, 2001). According to van Rijn (1993), initiation of motion in combined current and wave motion can also be expressed in terms of the Shields parameters, provided that the "wave period-averaged absolute bed-shear stress" is used.…”

Section: Introductionmentioning

confidence: 99%

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Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Zuo¹

2018

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Although all care is taken to ensure integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers, the author nor IHE Delft for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein. A pdf version of this work will be made available as Open Access via http://repository.tudelft.nl/ihe. This version is licensed under the Creative Commons To my family AbstractThe evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. Inspired by the Caofeidian sea area in Bohai Bay, China, this study aims to better understand silty sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL), and to improve our modelling approaches in predicting estuarine and coastal sediment transport.Field observations were carried out in northwestern Caofeidian sea area of Bohai Bay and field data were collected on several other silt-dominated coasts. Analysis shows that silt-dominated sediments are sensitive to flow dynamics: the suspended sediment concentrations (SSCs) increase rapidly under strong flow dynamics (i.e., waves or strong tidal currents which can stir up sediments), and high concentrations cause heavy sudden back siltation in navigation channels. In the following, details of silty sediment transport are studied, focusing on the BBL and high concentration layer (HCL).From laboratory experiments and theoretical analysis, an expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. The Shields number was revised by adding the cohesive force and additional static pressure, leading to an extended Shields curve.To study the HCL, a process based 1DV model was developed for flow-sediment dynamics near the bed in combined wave-current conditions. Based on the physical processes, special approaches for sediment movement were introduced, including approaches for different bed forms (rippled bed and 'flat-bed'), hindered settling, stratification effects, mobile bed effects, reference concentration and critical shear stress. The HCL was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the sediment concentration in the HCL. The results show that the HCL is affected by both flow dynamics and bed forms; the thickness of the HCL is about twice the height of the wave boundary layer; bed forms determine the shape of the concentration profile near the bottom, and flow dynamics determine the magnitude. For finer sediment, stratification effects and mobile bed effects impact the sediment concentration greatly.Finally, based on the 1DV model, the formulations of the mean sediment concentration profile of silty sediments were studied. By solving the time-averaged diffusion equation for SSC and considering the effects of bed forms, stratification and hindered settling, expressions for time-averaged SSC profile...

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Section: Analysis Of Sediment Incipient Motion Under Waves Andmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Zuo¹

2018

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“…In the new bed-load transport rate formula the bottom shear stress was calculated from Eq. (15), whereas τ⁎ cr is the critical Shields number calculated using the expression proposed by Tanaka and To (1995). The net sediment transport rate, averaged over one-period is expressed as follows:…”

Section: Bed-load Transport Rate Formulasmentioning

confidence: 99%

Effect of bed roughness on turbulent boundary layer and net sediment transport under asymmetric waves

Suntoyo

Tanaka

2009

Coastal Engineering

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“…Moreover, previous studies (e.g., Gonzalez-Radriguez and Madsen, 2007;Hemer et al, 2004;Jia et al, 2007;Myrhaug and Ong, 2009;van Gent et al, 2008;You, 2000You, , 2005 investigated wave-induced sediment erosion in laboratory and in-situ experiments, field observations, and theoretical models to find the effects of waves on sediment erosion and explore the mechanisms of the dynamic response of seabed sediment to waves. Although a number of studies (e.g., Chang et al, 2006;Liu and Jeng, 2007;Liu et al, 2006;Zen et al, 1998) showed that the mechanism of waveinduced seabed instability can be classified into two major types, shear failure and liquefaction, studies (e.g., Hemer et al, 2004;Myrhaug and Ong, 2009;Tanaka and van To, 1995) about seabed sediment erosion analysis in hydrodynamic conditions mainly focused on wave-induced stresses on the seabed and evaluation of resistance strengths of given seabed sediment. Generally, forces exerted on the seabed by waves can be classified into two types, level circulating shear stress and vertical pressure, which are considered the leading factors inducing shear failure and liquefaction of seabed sediment.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the variation of sediment erodibility under wave-loading conditions

et al. 2013

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Initial motion of sediment under waves and wave-current combined motions

Cited by 14 publications

References 9 publications

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Modelling and Analysis of Fine Sediment Transport in Wave-Current Bottom Boundary Layer

Effect of bed roughness on turbulent boundary layer and net sediment transport under asymmetric waves

Experimental study of the variation of sediment erodibility under wave-loading conditions

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