Opposing Wave Effect on Momentum Jets Spreading Rate

Ismail, Nabil M.; Wiegel, Robert L.

doi:10.1061/(asce)0733-950x(1983)109:4(465)

Cited by 34 publications

(23 citation statements)

References 6 publications

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“…This is most important for the three-dimensional momentum balance and/or in the presence of strong currents, e.g. when a rip current is widened by opposing waves, as observed by Ismail and Wiegel (1983) in the laboratory.…”

Section: Resultsmentioning

confidence: 99%

Explicit wave-averaged primitive equations using a generalized Lagrangian mean

2008

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The generalized Langrangian mean theory provides exact equations for general wave-turbulence-mean flow interactions in three dimensions. For practical applications, these equations must be closed by specifying the wave forcing terms. Here an approximate closure is obtained under the hypotheses of small surface slope, weak horizontal gradients of the water depth and mean current, and weak curvature of the mean current profile. These assumptions yield analytical expressions for the mean momentum and pressure forcing terms that can be expressed in terms of the wave spectrum. A vertical change of coordinate is then applied to obtain glm2z-RANS equations (55) and (57) with non-divergent mass transport in cartesian coordinates. To lowest order, agreement is found with Eulerian-mean theories, and the present approximation provides an explicit extension of known wave-averaged equations to short-scale variations of the wave field, and vertically varying currents only limited to weak or localized profile curvatures. Further, the underlying exact equations provide a natural framework for extensions to finite wave amplitudes and any realistic situation. The accuracy of the approximations is discussed using comparisons with exact numerical solutions for linear waves over arbitrary bottom slopes, for which the equations are still exact when properly accounting for partial standing waves. For finite amplitude waves it is found that the approximate solutions are probably accurate for ocean mixed layer modelling and shoaling waves, provided that an adequate turbulent closure is designed. However, for surf zone applications the approximations are expected to give only qualitative results due to the large influence of wave nonlinearity on the vertical profiles of wave forcing terms.

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Section: Resultsmentioning

confidence: 99%

Explicit wave-averaged primitive equations using a generalized Lagrangian mean

2008

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“…Waves affect the river mouth jet by increasing bed friction, which enhances jet spreading [Ismail and Wiegel, 1983] and jet stability [Jirka, 2001]. Ismail and Wiegel [1983], using theory and laboratory experiments, demonstrated that jet spreading is controlled by the ratio between wave momentum and jet momentum. Waves make river mouth bars form closer to the river mouth and impede the growth of lateral levees [Wright, 1977;Nardin et al, 2013].…”

Section: Wave Effect Of River Mouthsmentioning

confidence: 99%

Alongshore sediment bypassing as a control on river mouth morphodynamics

et al. 2016

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River mouths, shoreline locations where fluvial and coastal sediments are partitioned via erosion, trapping, and redistribution, are responsible for the ultimate sedimentary architecture of deltas and, because of their dynamic nature, also pose great management and engineering challenges. To investigate the interaction between fluvial and littoral processes at wave-dominated river mouths, we modeled their morphologic evolution using the coupled hydrodynamic and morphodynamic model Delft3D-SWAN. Model experiments replicate alongshore migration of river mouths, river mouth spit development, and eventual spit breaching, suggesting that these are emergent phenomena that can develop even under constant fluvial and wave conditions. Furthermore, we find that sediment bypassing of a river mouth develops though feedbacks between waves and river mouth morphology, resulting in either continuous bypassing pathways or episodic bar bypassing pathways. Model results demonstrate that waves refracting into the river mouth bar create a zone of low alongshore sediment transport updrift of the river mouth, which reduces sediment bypassing. Sediment bypassing, in turn, controls the river mouth migration rate and the size of the river mouth spit. As a result, an intermediate amount of river discharge maximizes river mouth migration. The fraction of alongshore sediment bypassing can be predicted from the balance between the jet and the wave momentum flux. Quantitative comparisons show a match between our modeled predictions of river mouth bypassing and migration rates observed in natural settings.

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“…Surface gravity waves can strongly affect tidal inlet hydrodynamics. Laboratory studies have shown that nonbreaking onshore‐propagating waves arrest and widen an ebb‐tidal jet [ Ismail and Wiegel , ]. Including wave effects in bottom stress formulations can affect modeled ebb‐tidal jets as they propagate on the inner shelf [ Rogowski et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Observations and modeling of a tidal inlet dye tracer plume

et al. 2016

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A 9 km long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on 7 May 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb‐tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb‐tidal jet because the obliquely incident breaking waves retarded the inlet‐mouth ebb‐tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to <4 m depth. Dye was then transported downcoast in the narrow (few 100 m wide) surfzone of the beach bordering the inlet at 0.3 m s−1 driven by wave breaking. Over 6 h, the dye plume is not significantly affected by buoyancy. Observed dye mass balances close indicating all released dye is accounted for. Modeled and observed dye behaviors are qualitatively similar. The model simulates well the evolution of the dye center of mass, lateral spreading, surface area, and maximum concentration, as well as regional (“inlet” and “ocean”) dye mass balances. This indicates that the model represents well the dynamics of the ebb‐tidal dye plume. Details of the dye transport pathways across the ebb shoal are modeled poorly perhaps owing to low‐resolution and smoothed model bathymetry. Wave forcing effects have a large impact on the dye transport.

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Opposing Wave Effect on Momentum Jets Spreading Rate

Cited by 34 publications

References 6 publications

Explicit wave-averaged primitive equations using a generalized Lagrangian mean

Explicit wave-averaged primitive equations using a generalized Lagrangian mean

Alongshore sediment bypassing as a control on river mouth morphodynamics

Observations and modeling of a tidal inlet dye tracer plume

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