Laboratory Measurements of Void Fraction and Turbulence in the Bore Region of Surf Zone Waves

Cox, Daniel T.; Shin, Sungwon

doi:10.1061/(asce)0733-9399(2003)129:10(1197)

Cited by 69 publications

(66 citation statements)

References 20 publications

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“…In contrast, for the second signal, it is difficult to ascertain whether the data reflect actually entrained bubbles or rather the passage of the free surface past the recording location. For both signals, the duration of air entrainment represents a small fraction of the total wave period (10 %), which is similar to the experiment of Cox & Shin (2003). Applying a model of the form α α av = a t T exp − b t T (12.1) is achievable but not particularly predictive, because figure 26 features increase and decay in void fraction at nearly the same rate.…”

Section: Aeration and Bubble Entrapmentmentioning

confidence: 56%

Turbulence structure and interaction with steep breaking waves

Lakehal

Liovic

2011

J. Fluid Mech.

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Large-eddy and interface simulation using an interface tracking-based multi-fluid flow solver is conducted to investigate the breaking of steep water waves on a beach of constant bed slope. The present investigation focuses mainly on the 'weak plunger' breaking wave type and provides a detailed analysis of the two-way interaction between the mean fluid flow and the sub-modal motions, encompassing wave dynamics and turbulence. The flow is analysed from two points of views: mean to sub-modal exchange, and wave to turbulence interaction within the sub-modal range. Wave growth and propagation are due to energy transfer from the mean flow to the waves, and transport of mean momentum by these waves. The vigorous downwellingupwelling patterns developing at the head and tail of each breaker are shown to generate both negative-and positive-signed energy exchange contributions in the thin sublayer underneath the water surface. The details of these exchange mechanisms are thoroughly discussed in this paper, together with the interplay between threedimensional small-scale breaking associated with turbulence and the dominant twodimensional wave motion. A conditional zonal analysis is proposed for the first time to understand the transient mechanisms of turbulent kinetic energy production, decay, diffusion and transport and their dependence and/or impact on surface wrinkling over the entire breaking process. The simulations provide a thorough picture of airliquid coherent structures that develop over the breaking process, and link them to the transient mechanisms responsible for their local incidence.

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Section: Aeration and Bubble Entrapmentmentioning

confidence: 56%

Turbulence structure and interaction with steep breaking waves

Lakehal

Liovic

2011

J. Fluid Mech.

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“…The kinetic energy was found to decay as t -1 , both experimentally (Rapp and Melville, 1990;Melville, 1991, 1992;Melville et al 2002;Drazen et al, 2008) and numerically (Chen et al, 1999;Lubin et al, 2006;Iafrati, 2009Iafrati, , 2011Lakehal andLiovic, 2011, Lubin andGlockner, 2015). The same decay rate was observed for all breaker types (spilling, weak plunging and plunging) (Melville et al 2002, Lubin andGlockner 2015), while similar integral properties in terms void fraction were comparable for different types of breaking waves (Cox and Shin, 2003;Blenkinsopp and Chaplin, 2007). Locations of air entrapment in the roller can be identified at the toe of the advancing roller, and on the whole interface of the roller, where multiple splashes are observed (Miller, 1976;Bonmarin, 1989;Nadaoka et al, 1989;Lin and Hwung, 1992;Rojen and Loewen, 2010;Lim et al, 2015).…”

mentioning

confidence: 74%

“…Lim et al (2015) reported similar findings. Cox and Shin (2003) found a linear growth followed by exponential decay, but with a different rate, which could be attributed to the shallow-water conditions used in their works.…”

Section: Flow Analogies or Not?mentioning

confidence: 93%

“…Several other works provided more comprehensive laboratory measurements of the void fraction in breaking waves, detailing the vertical and horizontal distributions of void fraction. Cox and Shin (2003) measured the void fraction in the aerated region at a point using a capacitance probe, and observed peak ensemble-averaged void fractions in the range of 15-20%. Surprisingly, they measured higher void fractions under the spilling breakers than under the plunging breakers.…”

Section: Flow Analogies or Not?mentioning

confidence: 99%

“…often suffered from limitations and inaccuracies (e.g. Cartellier and Achard 1991, Cox and Shin 2003, Chanson 2005. Phase-detection needle probes are intrusive point measurements, while BIV or PIV are non-intrusive but remain inaccurate when operated in highly aerated turbulent flows (bubble clustering, shape changes, light reflection, image processing technique and analysis).…”

Section: Flow Aeration and Bubble Sizesmentioning

confidence: 99%

See 2 more Smart Citations

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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Experimental study on plunging breaking waves in deep water

et al. 2015

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This study presents a unique data set that combines measurements of velocities and void fraction under an unsteady deep water plunging breaker in a laboratory. Flow properties in the aerated crest region of the breaking wave were measured using modified particle image velocimetry (PIV) and bubble image velocimetry (BIV). Results show that the maximum velocity in the plunging breaker reached 1.68C at the first impingement of the overturning water jet with C being the phase speed of the primary breaking wave, while the maximum velocity reached 2.14C at the beginning of the first splash-up. A similarity profile of void fraction was found in the successive impinging and splash-up rollers. In the highly foamy splashing roller, the increase of turbulent level and vorticity level were strongly correlated with the increase of void fraction when the range of void fraction was between 0 and 0.4 (from the trough level to approximately the center of the roller). The levels became constant when void fraction was greater than 0.5. The mass flux, momentum flux, kinetic energy, potential energy, and total energy were computed and compared with and without the void fraction being accounted for. The results show that all the mean and turbulence properties related to the air-water mixture are considerably overestimated unless void fraction is considered. When including the density variation due to the air bubbles, the wave energy dissipated exponentially a short distance after breaking; about 54% and 85% of the total energy dissipated within one and two wavelengths beyond the breaking wave impingement point, respectively.

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Laboratory Measurements of Void Fraction and Turbulence in the Bore Region of Surf Zone Waves

Cited by 69 publications

References 20 publications

Turbulence structure and interaction with steep breaking waves

Turbulence structure and interaction with steep breaking waves

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

Experimental study on plunging breaking waves in deep water

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