Pattern formation of underwater sand ripples with a skewed drive

Bundgaard, Frederik; Ellegaard, C.; Scheibye-Knudsen, K.; Bohr, Tomas; Sams, Thomas

doi:10.1103/physreve.70.066207

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…Laboratory and theoretical studies of such types of ripples have shown that some 3D ripple types occur as stable bedforms under constant oscillatory-flow conditions (e.g. Bagnold, 1946;Silvester, 1972Silvester, , 1975Matsunaga and Honji, 1980;Vittori and Blondeaux, 1992;Jan and Lin, 1998;Roos and Blondeaux, 2001), but other types emerge as ephemeral features during the process of ripple deformation in response to a change in near-bottom flow conditions (Hansen et al, 2001a(Hansen et al, , 2001bBundgaard et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…It could be widely accepted that 3D-patterned transitional ripples appear after oscillatory flow changes from a direction that is perpendicular to the crest line of the pre-existing ripples to one that is oblique or parallel (Bundgaard et al, 2004). However, through their oscillatory-bed experiment, Hansen et al (2001aHansen et al ( , 2001b have shown that ephemeral 3D-patterned ripples emerge even when the oscillatory flow direction does not change.…”

Section: Introductionmentioning

confidence: 99%

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Transient three‐dimensional‐patterned ripples appear during deformation of a two‐dimensional ripple field under wave‐induced oscillatory flow

Sekiguchi

2009

Earth Surf Processes Landf

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Wave-flume experiments on the process of deformation of pre-existing two-dimensional ripples revealed that one of two distinct types of three-dimensional patterned ripple, the rhombic or the barrel type, emerged in the early stages of the experimental runs. Rhombic-type ripples were characterized by a staggered pattern of similar-sized mounds, whereas the barreltype ripples had a barrel-like plan shape arranged in echelons. The former ripples were formed under strongly asymmetrical flow conditions with large excursion distances of water particle motion near the pre-existing rippled bed, whereas the latter were formed under relatively symmetrical flow conditions with small excursion distances. The emergence of both types of ripples was also highly dependent on sediment grain size.The present experiment was performed in the similar manner to the experiment of Sunamura (2004, 2005a); pre-exisitng 2D ripples were deformed by wave-induced oscillatory flow. A wave flume was 14 m long, 25 cm wide, and 50 cm deep (Figure 1). A piston-type wave generator was fitted at one end of the flume, and a fixed slope of 1/20 was installed at the other end to decrease the energy of the reflected waves. A movable bed 3 m long, 25 cm wide, and 3 cm high and composed of mono-sized sand was placed in the horizontal portion of the flume. Well-sorted quartz sands

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient three‐dimensional‐patterned ripples appear during deformation of a two‐dimensional ripple field under wave‐induced oscillatory flow

Sekiguchi

2009

Earth Surf Processes Landf

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“…, oscillatory-flow ripple , Nielsen, 1979Bagnold, 1946Traykovski et al, 1999Evans, 1943Shulyak, 1963Lofquist, 1978Traykovski et al 1999Hansen et al 2001a, b Bundgaard et al, 2004Davis et al, 2004;Sunamura, 2004, 2005;Sekiguchi, 2005Sekiguchi, , 2009Smith and Sleath, 2005;Testik et al, 2005;Doucette andO Donoghue, 2006 , Shulyak, 1963;Sekiguchi, 2005Sekiguchi, , 2009Davis et al, 2004;Sunamura, 2004, 2005;Testik et al, 2005Lofquist, 1978Doucette andO Donoghue, 2006 Hansen et al, 2001a, b;Bundgaard et al, 2004;Smith and Sleath, 2005 Hansen et al, 2001a, b;Bundgaard et al, 2004;Davis et al, 2004;Sekiguchi, 2005Sekiguchi, , 2009Sunamura, 2004, 2005;Smith and Sleath, 2005;Testik et al, 2005;Doucette and O Donoghue, 2006Bundgaard et al, 2004Hansen et al, 2001aSunamura, 2004, 2005 : λ e /λ i > λ e /λ i > 1 λ e Hansen et al, 2001a, b;Bundgaard et al, 2004;…”

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confidence: 99%

A brief review of transition processes of wave ripples

Sekiguchi¹

2011

Jour. Geol. Soc. Japan

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Wave ripples forming under stable oscillatory-flow conditions have a particular set of morphologies, dimensions, and crest orientations. With any significant change in the hydraulic conditions, the wave ripples lose their original equilibrium configuration, take transient forms, and eventually attain a new equilibrium state. This transition process depends on ( ) the ratio of the wavelengths of the original ripples to the renewed equilibrium ripples (λ e /λ i ), ( ) the degree of asymmetry in oscillatory flow, and ( ) sediment grain size when a new oscillatory flow is perpendicular to the crest lines of pre-existing ripples. Distinctive transient ripples, which tentatively appear (and then disappear) during the period of modification, are likely to be preserved in the geological record when λ e /λ i < . The analysis of such ripples can benefit estimations of paleohydraulic conditions.

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Instabilities and patterns in horizontally oscillating particulate suspension

Alam

Khalili

2008

Phys. Rev. E

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The mean flow and the linear stability characteristics of a two-dimensional particulate suspension, driven horizontally via harmonic oscillation, are analyzed. A constitutive model based on the kinetic theory of granular materials, which takes into account the dissipative collisional interactions among particles as well as their interactions with the interstitial fluid, is used; the effects of the interstitial fluid are incorporated in the balance equations for the particle phase. Assuming that the suspension is thin along the vertical direction, the effects of driving are incorporated into the governing equations in a mean-field manner. Using Floquet theory, a linear stability analysis of the time-periodic mean flow indicates that the oscillatory suspension supports stationary- and traveling-wave instabilities which correspond to particle banding patterns that are aligned parallel or orthogonal or at an oblique angle to the driving direction. The effects of external driving parameters and various system control parameters on the phase diagram of instabilities are studied. The fluid-particle interaction is shown to be responsible for the emergence of traveling instabilities in this flow.

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Pattern formation of underwater sand ripples with a skewed drive

Cited by 5 publications

References 18 publications

Transient three‐dimensional‐patterned ripples appear during deformation of a two‐dimensional ripple field under wave‐induced oscillatory flow

Transient three‐dimensional‐patterned ripples appear during deformation of a two‐dimensional ripple field under wave‐induced oscillatory flow

A brief review of transition processes of wave ripples

Instabilities and patterns in horizontally oscillating particulate suspension

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