The dynamics of strong turbulence at free surfaces. Part 1. Description

Brocchini, Maurizio; Peregrine, D. H.

doi:10.1017/s0022112001006012

Cited by 263 publications

(149 citation statements)

References 64 publications

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“…Further links were developed between breaking waves and steady flow configurations. These encompassed comparisons between plunging breakers and plunging jets (Cipriano and Blanchard 1981, Hubbard et al 1987, Chanson and Cumming 1994, Oguz et al 1995, Chanson et al 2002, Salter et al 2014, between spilling breakers and stationary hydraulic jumps (Longuet-Higgins 1973, Peregrine and Svendsen 1978, Madsen 1981, Brocchini et al 2001a, and between spilling breakers and translating hydraulic jumps (also called positive surges or tidal bores) (Longuet-Higgins 1973, Peregrine and Svendsen 1978, Brocchini and Peregrine 2001b. In parallel, there have been numerous discussions about the similarities and differences between stationary and translating hydraulic jumps (e.g.…”

Section: Flow Analogies or Not?mentioning

confidence: 99%

Are breaking waves, bores, surges and jumps the same flow?

Lubin

Chanson

2016

Environ Fluid Mech

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The flow structure in the aerated region of the roller generated by breaking waves remains a great challenge to study, with large quantities of entrained air and turbulence interactions making it very difficult to investigate in details. A number of analogies were proposed between breaking waves in deep or shallow water, tidal bores and hydraulic jumps. Many numerical models used to simulate waves in the surf zone do not implicitly simulate the breaking process of the waves, but are required to parameterise the wave-breaking effects, thus relying on experimental data. Analogies are also assumed to quantify the roller dynamics and the energy dissipation. The scope of this paper is to review the different analogies proposed in the literature and to discuss current practices. A thorough survey is offered and a discussion is developed an aimed at improving the use of possible breaking proxies. The most recent data are revisited and scrutinised for the use of most advanced numerical models to educe the surf zone hydrodynamics. In particular, the roller dynamics and geometrical characteristics are discussed. An open discussion is proposed to explore the actual practices and propose perspectives based on the most appropriate analogy, namely the tidal bore.

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Section: Flow Analogies or Not?mentioning

confidence: 99%

Are breaking waves, bores, surges and jumps the same flow?

Lubin

Chanson

2016

Environ Fluid Mech

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“…It is acknowledged that such scars are linked with some discontinuity in turbulence characteristics and physiochemical properties (e.g. Simpson, 1997;Brocchini and Peregrine, 2001;Tamburrino and Gulliver, 2007). The impact of raindrops generated waves and ripples at the water surface and their characteristics were functions of local surface tension.…”

Section: Surface Scars and Transient Frontsmentioning

confidence: 99%

Turbulence characteristics of a small subtropical estuary during and after some moderate rainfall

Trevethan

Chanson

Brown

2008

Estuarine, Coastal and Shelf Science

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Keywords: turbulence small subtropical estuary covariances triple correlations field measurements acoustic Doppler velocimetry rainfall runoff a b s t r a c tIn natural estuaries, scalar diffusion and dispersion are driven by turbulence. In the present study, detailed turbulence measurements were conducted in a small subtropical estuary with semi-diurnal tides under neap tide conditions. Three acoustic Doppler velocimeters were installed mid-estuary at fixed locations close together. The units were sampled simultaneously and continuously at relatively high frequency for 50 h. The results illustrated the influence of tidal forcing in the small estuary, although lowfrequency longitudinal velocity oscillations were observed and believed to be induced by external resonance. The boundary shear stress data implied that the turbulent shear in the lower flow region was one order of magnitude larger than the boundary shear itself. The observation differed from turbulence data in a laboratory channel, but a key feature of natural estuary flow was the significant threedimensional effects associated with strong secondary currents including transverse shear events. The velocity covariances and triple correlations, as well as the backscatter intensity and covariances, were calculated for the entire field study. The covariances of the longitudinal velocity component showed some tidal trend, while the covariances of the transverse horizontal velocity component exhibited trends that reflected changes in secondary current patterns between ebb and flood tides. The triple correlation data tended to show some differences between ebb and flood tides. The acoustic backscatter intensity data were characterised by large fluctuations during the entire study, with dimensionless fluctuation intensity I 0 b =I b between 0.46 and 0.54. An unusual feature of the field study was some moderate rainfall prior to and during the first part of the sampling period. Visual observations showed some surface scars and marked channels, while some mini transient fronts were observed.

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“…When a vortex is produced beneath the surface in a breaking process, its rotational velocity reduces the local pressure, thereby deforming the local surface into so-called 'scars'. Brocchini and Peregrine [2001] defined a scar to be 'a parallel line to wave direction near the wave crest on the free-surface where fluid is entrained downward from the surface layer'. When two counterrotating vortices located horizontally beneath the surface induce upwelling flow toward the surface, the surface is lifted, forming a domelike region over the vortices [Sarpkaya, 1996]; in this region, the resulting divergent surface flow replaces the surface with upwelling inner fluid (see Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves

Watanabe

Mori

2008

J. Geophys. Res.

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[1] When ocean waves reach a surf zone, jets projecting from the breakers splash sequentially, producing horizontal roller vortices beneath the jets and longitudinal counterrotating vortices behind the rollers; these vortices organize into three-dimensional structures that evolve into a turbulent bore with wave propagation. This disrupts any uniform temperature distributions on the surface, creating heterogeneous patterns of surface temperatures. In this study, we extracted surface temperature distributions from infrared measurements in small-and large-scale wave flumes, then used those data to study the renewed surfaces created by subsurface vortices beneath spilling and plunging breakers. In our large-scale experiments, temporal and spatial scales of surface renewal and surface recovery were consistent with earlier work; however, in our small-scale experiments, the spatial scales showed significant deviations from earlier in situ observations. These inconsistencies may be attributed to scale effects for subsurface vortices, and we show that the Froude number (Fr) can be used to characterize the initial formation of longitudinal counterrotating vortices. Further, for turbulent flows fully developed by wave breaking in a bore region, the frequency of surface renewal correlates exponentially with Reynolds number (Re). The computed vorticity on the breaking wave surface exhibits local patterns which correlate strongly with the gravity induced counterrotating vortices, which in turn renew the rear-facing surface of the breaking waves. In contrast the turbulent bore which precedes the wave crest rapidly disturbs and renews the surface in front of the crest. These two different mechanisms for surface renewal, during the nearshore breaking process, lead to modulations in the surface temperature distribution and changes in thermal diffusivity during the propagation of the breaking wave.Citation: Watanabe, Y., and N. Mori (2008), Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves,

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The dynamics of strong turbulence at free surfaces. Part 1. Description

Cited by 263 publications

References 64 publications

Are breaking waves, bores, surges and jumps the same flow?

Are breaking waves, bores, surges and jumps the same flow?

Turbulence characteristics of a small subtropical estuary during and after some moderate rainfall

Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves

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