Turbulence in the swash and surf zones: a review

Longo, Sandro; Petti, Marco; Losada, Íñigo J.

doi:10.1016/s0378-3839(02)00031-5

Cited by 94 publications

(50 citation statements)

References 107 publications

(115 reference statements)

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“…If the separation distance is less than the dominant vertical turbulence length scale, turbulence components are correlated and will be eliminated by differencing, artificially reducing the Reynolds stress estimates. In the present work, the separation distance between adjacent ADVOs (;0.2 m) is small relative to turbulence length scales beneath breaking waves (;0.1h -0.3h) reported in Pedersen et al (1998) and Longo et al (2002). Figure 6 and the associated linear regression statistics indicate a clear effect of turbulence correlation error as Reynolds stress estimates increase in magnitude with separation distance: the constant of proportionality m of 1(3) versus 1(2) and of 3(1) versus 3(2) Reynolds stress estimates are all above 1.…”

Section: Reynolds Stress Estimation Methodsmentioning

confidence: 99%

Observations of Turbulence within a Natural Surf Zone

Ruessink

2010

Journal of Physical Oceanography

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Here, the Reynolds stresses hu9w9i and hy9w9i, where u9, y9, and w9 are the cross-shore, alongshore, and vertical turbulence velocities, respectively, and the angle brackets represent time averaging, are used to diagnose turbulence dynamics beneath natural breaking surf-zone waves. The data were collected at Truc Vert Beach, France, during a 12-day period in 1-3-m water depth with strong cross-shore and alongshore currents under high-energy wave conditions (offshore significant wave heights ranged between 2 and 8 m). The hu9w9i term is predominantly negative, increases with the ratio of wave height H s to water depth h (;degree of wave breaking), and decreases in magnitude toward the bed. This supports the view that the cross-shore shear stress is due to breaking-induced vortices that transport high-speed cross-shore flow downward and disintegrate close to the bed. The occasional positive sign of hu9w9i within the lower 15%-20% of the water column indicates that sometimes surface-generated turbulence is overwhelmed by bed-generated turbulence, but the conditions when this happens are not clear from the data. The term hy9w9i is persistently of opposite sign to the alongshore mean current and decreases with height above the seabed, implying that hy9w9i is due to bottom boundary layer processes rather than surface-generated turbulence. The bottom drag coefficient amounted to 1.6 3 10 23 , similar to earlier observations. As in other high-Reynolds-number geophysical flows, time series of u9w9 and y9w9 comprise intermittently large, short-duration (here, ;1 s) stress events that in the data contribute considerably to the net stress in only 3%-15% of the time. The data further show that the turbulent kinetic energy is depth uniform and increases with H s /h. The depth-averaged Froudescaled turbulent kinetic energy beneath surf-zone bores is 0.025, a factor of 2 to 3 less than observed beneath regular laboratory waves.

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Section: Reynolds Stress Estimation Methodsmentioning

confidence: 99%

Observations of Turbulence within a Natural Surf Zone

Ruessink

2010

Journal of Physical Oceanography

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“…Shortly afterward, the flow evolves from subcritical to supercritical as the favorable pressure gradient becomes increasingly stronger during the backwash phase [Baldock and Hughes, 2006]. Sediment transport is then dominated by bed-generated turbulence [Longo et al, 2002;Cowen et al, 2003;Zhang and Liu, 2008;Lanckriet and Puleo, 2013] that may also mobilize sediment as sheet flow [Hughes et al, 2007;Lanckriet et al, 2014]. The relative dominance of the different flow phases (i.e., uprush versus backwash asymmetry) during a swash cycle largely depends on the beach face slope and incident wave conditions [Masselink and Puleo, 2006] and is known to have a large influence controlling the overall morphological response of the beach [Osborne and Rooker, 1999;Blenkinsopp et al, 2011;Puleo et al, 2014a;Masselink et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

et al. 2015

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Boundary layer dynamics are investigated using a 2‐D numerical model that solves the Volume‐Averaged Reynolds‐Averaged Navier‐Stokes equations, with a VOF‐tracking scheme and a k ‐ ϵ turbulence closure. The model is validated with highly resolved data of dam break driven swash flows over gravel impermeable and permeable beds. The spatial gradients of the velocity, bed shear stress, and turbulence intensity terms are investigated with reference to bottom boundary layer (BL) dynamics. Numerical results show that the mean vorticity responds to flow divergence/convergence at the surface that result from accelerating/decelerating portions of the flow, bed shear stress, and sinking/injection of turbulence due to infiltration/exfiltration. Hence, the zero up‐crossing of the vorticity is employed as a proxy of the BL thickness inside the shallow swash zone flows. During the uprush phase, the BL develops almost instantaneously with bore arrival and fluctuates below the surface due to flow instabilities and related horizontal straining. In contrast, during the backwash phase, the BL grows quasi‐linearly with less influence of surface‐induced forces. However, the infiltration produces a reduction of the maximum excursion and duration of the swash event. These effects have important implications for the BL development. The numerical results suggest that the BL growth rate deviates rapidly from a quasi‐linear trend if the infiltration is dominant during the initial backwash phase and the flat plate boundary layer theory may no longer be applicable under these conditions.

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“…Two first mentioned methods have been useful to describe the morphodynamic that influences the assessment of runup such as: the beach state, reflective or dissipative, (Kiyoshi Horikawa, 1988), turbulence in the swash (Longo, 2002), etc. The complexity in the hydrodynamic processes within the surf zone and its interaction with beach morphology make hard to develop numerical models for resolving applicable equations (Kobayashi, 1997).…”

Section: Literature Reviewmentioning

confidence: 99%

Physical Model and Revision of Theoretical Runup

Peña¹,

Sánchez²,

Díaz³

et al. 2012

Int. Conf. Coastal. Eng.

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Several formulations deduced from empirical studies are available for runup estimation. Scattering is high when applied to practical cases. Through a state of the art best formulations are chosen. These equations are also studied in a physical model carried out in the Laboratory for Maritime Experimentation of CEDEX with three beaches with slopes 1/20, 1/30 and 1/50 and with sand bed. The performance of each formulation is discussed. A new formulation is proposed in order to give more weight to the beach slope thus reducing scatter.

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Turbulence in the swash and surf zones: a review

Cited by 94 publications

References 107 publications

Observations of Turbulence within a Natural Surf Zone

Observations of Turbulence within a Natural Surf Zone

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

Physical Model and Revision of Theoretical Runup

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