Steady Streaming Induced by Asymmetric Oscillatory Flows over a Rippled Bed

Scandura, Pietro; Faraci, Carla; Blondeaux, Paolo

doi:10.3390/jmse8020142

Cited by 4 publications

(2 citation statements)

References 16 publications

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“…Consequently, comparison of space and time averaged velocity profiles in the three different flow conditions carried out on a fixed bed (CO, WO, and WC) leads to the observation that the WO profile returns a negative bed velocity (see Figure 8). Such behavior is a direct consequence of the existence of a steady streaming, which increases with increasing Reynolds numbers [32], which can be significantly larger than that predicted for laminar flows over flat beds. Accordingly, positive streaming can also be observed upwards, and it is related to the existence of positive values of time-averaged Reynolds stresses [32].…”

Section: Fixed Bedmentioning

confidence: 79%

“…Such behavior is a direct consequence of the existence of a steady streaming, which increases with increasing Reynolds numbers [32], which can be significantly larger than that predicted for laminar flows over flat beds. Accordingly, positive streaming can also be observed upwards, and it is related to the existence of positive values of time-averaged Reynolds stresses [32]. This inversion was also found in the WC case, though to a lesser extent with respect to the WO case.…”

Section: Fixed Bedmentioning

confidence: 79%

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Collinear Interaction of Waves and Current in the Presence of Ripple in the U-Tube

Ruggeri

Faraci

2022

Water

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Ripple formation and evolution as well as vortex separation along the bedform profile strongly influence surface waves and sediment transport. These features were investigated in a U-Tube at the Hydraulics Laboratory of the University of Messina. During the experimental campaign, tests in the presence of wave only, current only, and collinear wave plus current in wave dominated regime were carried out. The experiments involved both live bed and fixed bed conditions. It was observed that, when the current superimposes to the wave, a longer time is required for the bedforms to stabilize; the vortex separating at the ripple crest reduces with respect to the wave only case. Accordingly, in the fixed rippled bed case, velocity measured in current only condition is larger than that in the wave plus current flow. As vortex shedding influences the way sediments are transported close to the bed, the obtained results may improve the present knowledge on wave current interaction in the presence of bedforms with repercussions in turn on sediment dynamics.

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Section: Fixed Bedmentioning

confidence: 79%

Section: Fixed Bedmentioning

confidence: 79%

Collinear Interaction of Waves and Current in the Presence of Ripple in the U-Tube

Ruggeri

Faraci

2022

Water

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Effect of surface wave skewness on near-bed sediment transport velocity

Stachurska

Staroszczyk

2021

Continental Shelf Research

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Mass transport at the bottom of propagating surface waves over a rippled bottom

Vittori,

Blondeaux

2024

Physics of Fluids

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The sea surface can be described by means of the superposition of many sinusoidal functions. However, quite often the amplitude of each component turns out to be much smaller than its wavelength, and any component evolves independently of the others. Hence, it is common to investigate the dynamics of a simple monochromatic surface wave. Hereinafter, the flow generated by a monochromatic surface wave within the bottom boundary layer over a rippled sea bed is determined by means of the numerical integration of vorticity and continuity equations. The forcing term that drives the fluid motion within the boundary layer is evaluated assuming that the steepness of the monochromatic surface wave is much smaller than one and considering the first term of the Stokes expansion. Even though the irrotational flow that forces the viscous rotational flow near the sea bottom is symmetric with respect to the ripple crests, Blondeaux and Vittori [“A route to chaos in an oscillatory flow: Feigenbaum scenario,” Phys. Fluids A 3(11), 2492–2495 (1991a)] showed that the symmetry of the flow field is broken when the Reynolds number becomes larger than a threshold value Rδ,t1 that depends on the geometrical characteristics of the ripples. The results of Blondeaux and Vittori [“A route to chaos in an oscillatory flow: Feigenbaum scenario,” Phys. Fluids A 3(11), 2492–2495 (1991a)] suggest that, when the Reynolds number is larger than Rδ,t1 but not too far from it, a steady current is also generated. Hereinafter, the steady velocity component is determined as a function of the ripple characteristics.

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Steady Streaming Induced by Asymmetric Oscillatory Flows over a Rippled Bed

Cited by 4 publications

References 16 publications

Collinear Interaction of Waves and Current in the Presence of Ripple in the U-Tube

Collinear Interaction of Waves and Current in the Presence of Ripple in the U-Tube

Effect of surface wave skewness on near-bed sediment transport velocity

Mass transport at the bottom of propagating surface waves over a rippled bottom

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