Growth and dissipation of wind-forced, deep-water waves

Grare, Laurent; Peirson, William L.; Branger, Hubert; Walker, James W.; Giovanangeli, Jean‐Paul; Makin, V. K.

doi:10.1017/jfm.2013.88

Cited by 87 publications

(136 citation statements)

References 69 publications

(157 reference statements)

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“…Figure 5b shows b as a function of the initial wave slope S in the DNS, and we observe a very good agreement for strong plunging waves with the semi-empirical result given by Eq. 3.4 initially derived from laboratory data (Drazen et al 2008;Romero et al 2012), see also data from Grare et al (2013) and two-dimensional numerical simulations from Deike et al (2015). This confirms that the present three-dimensional DNS captures the dissipative scales of the breaking wave process.…”

Section: Energy Dissipationsupporting

confidence: 83%

“…This inertial model, based on a simple physical argument for strong plunging waves, has been confirmed through extensive experimental studies and modeling, well beyond the region of validity of the initial hypothesis (Romero et al 2012;Grare et al 2013;Pizzo & Melville 2013;Melville & Fedorov 2015;Deike et al 2015). Note that proportionality between the initial slope and the slope at breaking is also true in our DNS of steep Stokes waves, and following the definition of Drazen et al (2008) where h is the vertical distance the breaking wave toe travels before impact, hk = −0.05 + S for both the 3D DNS presented here and the 2D results presented in Deike et al (2015).…”

Section: Energy Dissipationmentioning

confidence: 63%

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Air entrainment and bubble statistics in breaking waves

2016

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We investigate air entrainment and bubble statistics in three-dimensional breaking waves through novel direct numerical simulations of the two-phase air-water flow, resolving the length scales relevant for the bubble formation problem, the capillary length and the Hinze scale. The dissipation due to breaking is found to be in good agreement with previous experimental observations and inertial-scaling arguments. The air-entrainment properties and bubble-size statistics are investigated for various initial characteristic wave slopes. For radii larger than the Hinze scale, the bubble size distribution, can be described by N (r, t) = B(V 0 /2π)(ε(t − ∆τ )/W g)r −10/3 r −2/3 m during the active breaking stages, where ε(t − ∆τ ) is the time dependent turbulent dissipation rate, with ∆τ the collapse time of the initial air pocket entrained by the breaking wave, W a weighted vertical velocity of the bubble plume, r m the maximum bubble radius, g gravity, V 0 the initial volume of air entrained, r the bubble radius and B a dimensionless constant. The active breaking time-averaged bubble size distribution is described bȳ N (r) = B(1/2π)( l L c /W gρ)r −10/3 r −2/3 m , where l is the wave dissipation rate per unit length of breaking crest, ρ the water density and L c the length of breaking crest. Finally, the averaged total volume of entrained air,V , per breaking event can be simply related to l byV = B( l L c /W gρ), which leads to a relationship to a characteristic slope, S, of V ∝ S 5/2 . We propose a phenomenological turbulent bubble break-up model, based on earlier models and the balance between mechanical dissipation and work done against buoyancy forces. The model is consistent with the numerical results and existing experimental results.

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Section: Energy Dissipationsupporting

confidence: 83%

Section: Energy Dissipationmentioning

confidence: 63%

Air entrainment and bubble statistics in breaking waves

2016

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“…The surface viscous stress then becomes negative (below the flow reversal region), and remains close to zero up to k p x = 3, and then slowly increases back up to ≈ 50% of the total stress, on the windward side of the next downwind wave. These stress measurements compare very well with the measurements of Banner and Peirson (1998) (made on the waterside) and the measurements of Grare et al (2013b) …”

Section: Instantaneous 2d Fieldssupporting

confidence: 80%

“…Later, Veron et al (2007) were able to estimate viscous stresses in the air above wind-generated waves by PIV. Grare (2009) and Grare et al (2013b) obtained single point airflow velocity measurements above laboratory wind waves, by repeatedly plunging a hot wire anemometer into the water for each experimental condition. Using this innovative method, they measured vertical airflow velocity profiles with 1 velocity measurement every 50 μm, and computed viscous and form drags above wind waves (Grare et al 2013b).…”

Section: Introductionmentioning

confidence: 99%

“…Grare (2009) and Grare et al (2013b) obtained single point airflow velocity measurements above laboratory wind waves, by repeatedly plunging a hot wire anemometer into the water for each experimental condition. Using this innovative method, they measured vertical airflow velocity profiles with 1 velocity measurement every 50 μm, and computed viscous and form drags above wind waves (Grare et al 2013b). However, due to the one-dimensionality of their measurement system, wave phase detection was only indirectly achieved using a single point wave gauge (Grare 2009); additionally the instantaneous spatial along-wave structure of the airflow was not resolved.…”

Section: Introductionmentioning

confidence: 99%

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Airflow measurements at a wavy air–water interface using PIV and LIF

Buckley

Véron

2017

Exp Fluids

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geophysical sphere, which largely motivates this study, fluxes of momentum and scalars across the wavy air-sea interface provide boundary conditions for both the atmosphere and the oceans and are therefore, pivotal in controlling the evolution of weather and climate. These fluxes are affected by fine-scale, coupled dynamics above and below the wavy ocean surface. In fact, the surface waves significantly modify the boundary layers on both sides of the interface and it is now well established that it is through waverelated dynamical processes that the air and water boundary layers are coupled (see Sullivan and McWilliams (2010) for a review on the topic).On the water side, for example, it has been shown that the interaction between the wave-induced Lagrangian mass transport, i.e. the Stokes drift, and the surface shear current, leads to the generation of Langmuir circulations, causing significant mixing of the water column (Skyllingstad and Denbo 1995;McWilliams et al. 1997;Noh et al. 2005;Li et al. 2005;Harcourt and D'Asaro 2008; Grant and E 2009;Veron et al. 2009;Kukulka et al. 2010;Belcher et al. 2012;D'Asaro 2014). When surface waves break, the turbulence injected into the water column also significantly enhances surface mixing Melville et al. 1998;Veron and Melville 1999;Melville et al. 2002;Thorpe et al. 2003;Gemmrich and Farmer 2004) and leads to substantial deviations from the classical theories (Agrawal et al. 1992;Thorpe 1993;Melville 1994;Anis and Moum 1995;Melville 1996;Terray et al. 1996; Veron and Melville 2001) and causes significant energy dissipation (Banner et al. 2014;Thomson et al. 2016;Schwendeman et al. 2014;Zappa et al. 2016; Melville 2013, 2015).On the air side, it is clear that surface wave processes also play an important role in the kinematics and dynamics of the boundary layer (e.g. Janssen 1989; Komen et al. 1994;Belcher and Hunt 1998;Hristov et al. 1998; Abstract Physical phenomena at an air-water interface are of interest in a variety of flows with both industrial and natural/environmental applications. In this paper, we present novel experimental techniques incorporating a multi-camera multi-laser instrumentation in a combined particle image velocimetry and laser-induced fluorescence system. The system yields accurate surface detection thus enabling velocity measurements to be performed very close to the interface. In the application presented here, we show results from a laboratory study of the turbulent airflow over wind driven surface waves. Accurate detection of the wavy air-water interface further yields a curvilinear coordinate system that grants practical and easy implementation of ensemble and phase averaging routines. In turn, these averaging techniques allow for the separation of mean, surface wave coherent, and turbulent velocity fields. In this paper, we describe the instrumentation and techniques and show several data products obtained on the air-side of a wavy air-water interface.

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Air entrainment by breaking waves

Deike

Lenain

Melville

2017

Geophysical Research Letters

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We present an estimate of the total volume of entrained air by breaking waves in the open ocean, based on a model for a single breaking wave and the statistics of breaking waves measured in the field and described by the average length of breaking crests moving with speeds in the range (c,c + dc) per unit area of ocean surface, Λ(c)dc, introduced by Phillips (1985). By extending the single breaking wave model to the open ocean, we show that the volume flux of air entrained by breaking waves, VA (volume per unit ocean area per unit time, a velocity), is given by the third moment of Λ(c), modulated by a function of the wave slope. Using field measurements of the distribution Λ(c) and the wave spectrum, we obtain an estimate of the total volume flux of air entrained by breaking for a wide range of wind and wave conditions. These results pave the way for accurate remote sensing of the air entrained by breaking waves and subsequent estimates of the associated gas transfer.

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Growth and dissipation of wind-forced, deep-water waves

Cited by 87 publications

References 69 publications

Air entrainment and bubble statistics in breaking waves

Air entrainment and bubble statistics in breaking waves

Airflow measurements at a wavy air–water interface using PIV and LIF

Air entrainment by breaking waves

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