Numerical simulation of surf–swash zone motions and turbulent flow

Bakhtyar, Roham; Barry, David Andrew; Yeganeh‐Bakhtiary, Abbas; Ghaheri, Abbas

doi:10.1016/j.advwatres.2008.11.004

Cited by 48 publications

(54 citation statements)

References 37 publications

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“…Before the breaking zone, all models over-estimate the experimental results. The discrepancies between numerical and experimental results are likely due to the fact that the generation and transformation of bed friction-induced turbulence is not modeled properly [20]. However, from the breaking point to the swash zone, the results of the k-ε and RNG models are less than the experimental observations, while those of the k-ω model are higher.…”

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 42%

“…All the models give a higher undertow (bias = -2.88, -1.55 and -1.43 cms -1 for the k-ω, k-ε and RNG turbulence models, respectively) in the nearshore zone. Besides the experimental data, we also compared our model results with those of the singlephase flow model of Bakhtyar et al [20]. Figure 7 shows the cross-shore variation of the TKE for both of the experimental data and numerical results (using the single-phase and two-phase flow models) in the surf and swash zones.…”

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

“…All models show less satisfactory performance in the roller region, where there is higher velocity and momentum exchange. In the 20 rest of nearshore zone, all models show much better performance in predicting the undertow rather than the region close to the breaking points. The numerical results reveal that, for the three turbulence closure models considered, the two-phase flow model can predict well the undertow.…”

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

“…Furthermore, the k-ω turbulence cannot predict (accurately) the TKE in areas with strong acceleration like the inner surf and swash zones, where it over-predicts the experimental results. 19 The main sources for disagreement between numerical results and experimental data were discussed in detail in Bakhtyar et al [20].…”

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

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Air–water two-phase flow modeling of turbulent surf and swash zone wave motions

Bakhtyar

Razmi

Barry

et al. 2010

Advances in Water Resources

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Wave breaking and wave runup/rundown have a major influence on nearshore hydrodynamics, morphodynamics and beach evolution. In the case of wave breaking, there is significant mixing of air and water at the wave crest, along with relatively high kinetic energy, so prediction of the free surface is complicated. Most hydrodynamic studies of surf and swash zone are derived from single-phase flow, in which the role of air is ignored. Two-phase flow modeling, consisting of both phases of water and air, may be a good alternative numerical modeling approach for simulating nearshore hydrodynamics and, consequently, sediment transport. A two-phase flow tool can compute more realistically the shape of the free surface, while the effects of air are accounted for. This paper used models based on two-dimensional, two-phase Reynolds-Averaged NavierStokes equations, the Volume-Of-Fluid surface capturing technique and different turbulence closure models, i.e., k-ε, k-ω and Re-Normalized Group (RNG). Our numerical results were compared with the available experimental data. Comparison of the employed method with a model not utilizing a two-phase flow modeling demonstrates that including the air phase leads to improvement in simulation of wave characteristics, especially in the vicinity of the breaking point.The numerical results revealed that the RNG turbulence model yielded better predictions of nearshore zone hydrodynamics, although the k-ε model also gave satisfactory predictions. The model provides new insights for the wave, turbulence and means flow structure in the surf and swash zones.

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Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 42%

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

Section: Validation Of the Two-phase Flow Modelmentioning

confidence: 99%

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Air–water two-phase flow modeling of turbulent surf and swash zone wave motions

Bakhtyar

Razmi

Barry

et al. 2010

Advances in Water Resources

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“…Moreover, recent numerical studies [e.g., Brocchini and Baldock, 2008;Bakhtyar et al, 2009;Zhu and Dodd, 2013;Torres-Freyermuth et al, 2013] have provided additional information on the dynamics in this region, as they allow improved understanding of temporal and spatial variability of flow properties under different boundary/forcing conditions. From these studies, a general description of the swash cycle in relation to sediment transport is synthetized as follows.…”

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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References

2018

3D Modeling of Nonlinear Wave Phenomena on Shallow Water Surfaces

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Numerical simulation of surf–swash zone motions and turbulent flow

Cited by 48 publications

References 37 publications

Air–water two-phase flow modeling of turbulent surf and swash zone wave motions

Air–water two-phase flow modeling of turbulent surf and swash zone wave motions

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

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