Wave‐formed sand ripples at Duck, North Carolina

Hanes, Daniel M.; Alymov, Vadim; Chang, Yeon S.; Jette, Chris

doi:10.1029/2000jc000337

Cited by 88 publications

(112 citation statements)

References 25 publications

(16 reference statements)

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“…Recently, Hanes et al (2001) observed in the field long-wave ripples (LWR) with relatively small heights (ranging from 3 mm to 6 cm) and large lengths (ranging from 35 to 200 cm). LWR were observed to be not as dynamics as the small-wave ripples (SWR) commonly observed.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the wave-related ripple characteristics and induced bed shear stress

Camenen¹

2009

Estuarine, Coastal and Shelf Science

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A large data set on ripples was collected and examined. A set of new formulas for the prediction of the ripple characteristics is proposed with an emphasis on the disappearance of the ripples. The ripple wavelength was observed to be proportional to the bottom wave excursion but also to be a function of the grain-related Shields parameter and wave period parameter introduced by Mogridge et al. (1994). The ripple steepness was found to be nearly constant for orbital ripples, and with a sharp decrease for suborbital ripples. Two empirical functions are added including the effects of the critical Shields parameters (inception of transport and inception of sheet flow), i.e. giving the boundaries for the ripple existence's domain. The proposed formulas yield better prediction capabilities compared to the previously published formulas, especially when ripples are washed out. The effect of the ripple characteristics on the roughness height and the calculation of the bed shear stress is also discussed. It appeared that the bed shear stress calculation is more sensitive to the empirical coefficient a r introduced in the estimation of the ripple-induced roughness height or to the limits of existence of the ripples than the ripple characteristics themselves.

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Section: Introductionmentioning

confidence: 99%

Estimation of the wave-related ripple characteristics and induced bed shear stress

Camenen¹

2009

Estuarine, Coastal and Shelf Science

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“…Combined flows are difficult to produce in the laboratory, and the bed forms produced by combined flows include both 2D ripples and a variety of three-dimensional (3D) bed forms, posing a more complex predictive problem than pure wave-generated ripples. Field studies of bed forms produced by waves and currents include those by Amos et al [1988]; Li and Amos [1998]; Osborne and Vincent [1993]; Traykovski et al [1999]; Hanes et al [2001]; Smyth and Li [2005].…”

Section: Introductionmentioning

confidence: 99%

Bed forms created by simulated waves and currents in a large flume

et al. 2007

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[1] The morphology and evolution of bed forms created by combinations of waves and currents were investigated using an oscillating plate in a 4-m-wide flume. Current speed ranged from 0 to 30 cm/s, maximum oscillatory velocity ranged from 20 to 48 cm/s, oscillation period was 8 s (except for one run with 12 s period), and the median grain size was 0.27 mm. The angle between oscillations and current was 90°, 60°, or 45°. At the end of each run the sand bed was photographed and ripple dimensions were measured. Ripple wavelength was also determined from sonar images collected throughout the runs. Increasing the ratio of current to wave (i.e., oscillatory) velocity decreased ripple height and wavelength, in part because of the increased fluid excursion during the wave period. Increasing the ratio of current to waves, or decreasing the angle between current and waves, increased the three-dimensionality of bed forms. During the runs, ripple wavelength increased by a factor of about 2. The average number of wave periods for evolution of ripple wavelength to 90% of its final value was 184 for two-dimensional ripples starting from a flat bed. Bed form orientations at the end of each run were compared to four potential controlling factors: the directions of waves, current, maximum instantaneous bed shear stress, and maximum gross bed form normal transport (MGBNT). The directions of waves and of MGBNT were equally good predictors of bed form orientations, and were significantly better than the other two factors.

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“…CHANG AND HANES: MILDLY SLOPED LONG WAVE RIPPLES seabed exhibited LWR that are typical of the location [Hanes et al, 2001]. In these two data sets, however, the ABS was at relatively different locations on the ripple profile.…”

Section: C07022mentioning

confidence: 94%

“…Rather, they are parameterized by the hydraulic roughness. In order to examine the effects of bed roughness more effectively, we superimposed 20 SWR [Hanes et al, 2001] upon the LWR in the computational domain. The size of each SWR is 10 cm in length and 0.5 cm in height.…”

Section: Discussionmentioning

confidence: 99%

“…Acoustic instruments for measuring the SSC such as the Acoustic Backscatter System (ABS) have enabled the measurement of nearly instantaneous concentration profiles [Lee and Hanes, 1995;Osborne and Vincent, 1996;Thosteson and Hanes, 1998]. The Multiple Transducer Array (MTA) has enabled the measurement of bedforms in one dimension [Jette and Hanes, 1997;Hanes et al, 2001]. These and other acoustic instruments provide times series of fluid motions, SSC, and bedforms (see Thorne and Hanes [2002] for a summary).…”

Section: Introductionmentioning

confidence: 99%

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Suspended sediment and hydrodynamics above mildly sloped long wave ripples

Chang

2004

J. Geophys. Res.

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[1] We investigate the spatial and temporal distribution of suspended sediment and the associated hydrodynamics over mildly sloped long wave ripples on the inner shelf. These bedforms had wavelengths of approximately 1 m and heights of approximately 5 cm, in a mean water depth of 4 m. The vertical and temporal structures of the suspended sediment concentration (SSC) are consistent with the entrainment of sediment on the offshore flank of the ripple, and rapid vertical mixing at the time of flow reversal, followed by advection onshore by the onshore fluid motion. This work confirms that the mechanism for sediment suspension above low-amplitude, long wave ripples is similar to the vortex formation process expected over steeper vortex ripples. Numerical simulations of the flow using the Dune2d model indicate that a separated rotational flow structure is generated at the flank of the ripple on the seaward side of the ripple crest, near the time of flow reversal. The simulations indicate that only one vortex is formed during each wave period, in agreement with the field observations. This asymmetry is due mainly to the presence of an offshore mean near-bed current of approximately 6 to 8 cm/s. The SSC is calculated by the model and compared to the field observations. A hydraulic bed roughness of 10 to 15 median grain diameters (d 50 ) was used in order to match the model prediction to the observed SSC approximately 1 cm above the seabed (cab). However, the modeled SSC and turbulent kinetic energy were significantly lower than the field observations at elevations exceeding approximately 2 cab.

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Wave‐formed sand ripples at Duck, North Carolina

Cited by 88 publications

References 25 publications

Estimation of the wave-related ripple characteristics and induced bed shear stress

Estimation of the wave-related ripple characteristics and induced bed shear stress

Bed forms created by simulated waves and currents in a large flume

Suspended sediment and hydrodynamics above mildly sloped long wave ripples

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