Scarifying and fingering surfaces of plunging jets

Saruwatari, Ayumi; Watanabe, Yasunori; Ingram, David

doi:10.1016/j.coastaleng.2009.08.007

Cited by 22 publications

(21 citation statements)

References 16 publications

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“…The structures are observed to be aerated, as their mouths are attached to the free-surface while the other end is linked to the main tube of air. We do not noticed any bending at their extremities, nor continuous linking to neighbouring filaments to form loops (Watanabe et al 2005;Saruwatari et al 2009). The common point is the shear region in the saddlepoint, responsible for the stretch-and-intensification process of the filaments.…”

Section: Yesmentioning

confidence: 97%

“…Narayanaswamy & Dalrymple (2002) experimentally presented evidence of "fingers" appearing at the tip of the plunging jet, prior to impact. More recently, Saruwatari et al (2009) studied numerically the formation of fingers and scars at the surface of secondary planar jets and suggested that, as the influence of surface tension increases, the jet surface is prevented from being scarified and fingered. Handler et al (2012) experimentally investigated the generation of coherent elongated structures behind breaking waves.…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Numerical Simulations of Aerated Vortex Filaments Under Plunging Breaking Waves

Lubin

Glockner

2014

Int. Conf. Coastal. Eng.

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The scope of this work is to present and discuss the results obtained from simulating three-dimensional plunging breaking waves. A numerical tool based on the Navier-Stokes equations is used to describe the plunging breaking processes including overturning, splash-up and the occurrence of air entrainment. Initial 3D conditions corresponding to unstable periodic sinusoidal waves of large amplitudes in periodic domains are used to study the air entrainment occurring when waves break. The numerical results highlight the major role of this phenomenon in the energy dissipation process, through a high level of turbulence generation. The numerical model represents a substantial improvement in the numerical modelling of breaking waves since it includes the air entrainment process neglected in most previous existing models.

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Section: Yesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Numerical Simulations of Aerated Vortex Filaments Under Plunging Breaking Waves

Lubin

Glockner

2014

Int. Conf. Coastal. Eng.

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“…The size and population of spray droplets produced in a wave-breaking process are still indefinite because spray in a surf zone is produced through various mechanisms. de Leeuw (1999) observed that the number density of sea spray droplets of more than O(10 µm) in size in a surf zone was one to two orders of magnitude larger than that in the offshore region under a moderate wind condition, which is thought to be because of continuous aeration and spray production concentrated in a surf zone ( Fig.s 2 and 3 of Saruwatari et al, 2009). According to the relationship between evaporation velocity and falling velocity of spray, the most effective spray droplet size for heat transfer is O(10-100 µm) (Andreas, 1992), which coincides with the size range of spray droplets produced in a surf zone.…”

Section: Introductionmentioning

confidence: 99%

“…Spumes therefore are less dominant under a moderate wind condition. Depth-induced breaking waves cause production of spray in a coastal area since the jet of a breaking wave fragments into droplets through interaction between the water surface and vortices underneath the surface (Saruwatari et al, 2009). In addition, aeration induced by jet splashing intensifies production of film and jet droplets in a surf zone.…”

Section: Introductionmentioning

confidence: 99%

Relationship between latent heat of sea spray and uncertainty of a meteorological field

Saruwatari

Abe

2014

Applied Ocean Research

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A surf zone with large breaking waves produces more spray than do offshore regions. Latent heat of spray evaporation causes change in the surrounding temperature and wind velocity, resulting in further alterations in temperature, wind velocity and heat flux. Spray in a surf zone with large breaking waves may have unignorable effect on determination of a local meteorological field because of this interconnected relationship as well as its higher population than in the open ocean. In this study, the effects of the spray latent heat on a meteorological field were investigated. The authors propose a method for estimating latent heat of spray vaporization over the ocean. The method was applied to a meso-scale meteorological model to perform numerical experiments with consideration of heat flux by spray. Although the contribution of heat flux on the ocean was as small as 2.5%, fluctuations of air temperature and wind velocity increased over time due to the effects of spray. The fluctuations are thought to cause uncertainty in weather prediction. Numerical experiments with spray provided predictions of air temperature and wind velocity near a coast line that were consistent with observational data, especially when the population of spray droplets increased by two orders of magnitude as is often observed in a coastal area.

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“…In the surf zone, there is a variety of size ranges of the spray, each determined by the multitude of primary spray production mechanisms. These range from the finest (sea spray aerosol) created by bubble-bursting at the sea surface [3], through larger spume droplets created by the tearing of wave crests by the wind [4,5], to the largest droplets that are fragmented from finger jets formed by vorticity instability in plunging waves [6,7]. Furthermore, during storm events, when large ocean waves impact on breakwaters and coastal cliffs, sea sprays rising several tens of metres into the air have often been observed in coasts (figure 1a).…”

Section: Introductionmentioning

confidence: 99%

Size distributions of sprays produced by violent wave impacts on vertical sea walls

Watanabe

Ingram

2016

Proc. R. Soc. A.

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When a steep, breaking wave hits a vertical sea wall in shallow water, a flip-through event may occur, leading to the formation of an up-rushing planar jet. During such an event, a jet of water is ejected at a speed many times larger than the approaching wave's celerity. As the jet rises, the bounded fluid sheet ruptures to form vertical ligaments which subsequently break up to form droplets, creating a polydisperse spray. Experiments in the University of Hokkaido's 24 m flume measured the resulting droplet sizes using image analysis of high-speed video. Consideration of the mechanisms forming spray droplets shows that the number density of droplet sizes is directly proportional to a power p of the droplet radius: where p = −5/2 during the early break-up stage and p = −2 for the fully fragmented state. This was confirmed by experimental observations. Here, we show that the recorded droplet number density follows the lognormal probability distribution with parameters related to the elapsed time since the initial wave impact. This statistical model of polydisperse spray may provide a basis for modelling droplet advection during wave overtopping events, allowing atmospheric processes leading to enhanced fluxes of mass, moisture, heat and momentum in the spraymediated marine boundary layer over coasts to be described.

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Scarifying and fingering surfaces of plunging jets

Cited by 22 publications

References 16 publications

Three-Dimensional Numerical Simulations of Aerated Vortex Filaments Under Plunging Breaking Waves

Three-Dimensional Numerical Simulations of Aerated Vortex Filaments Under Plunging Breaking Waves

Relationship between latent heat of sea spray and uncertainty of a meteorological field

Size distributions of sprays produced by violent wave impacts on vertical sea walls

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