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In this paper a detailed analysis of undular bore dynamics in channels of variable cross-section is presented. Two undular bore regimes, low Froude number (LFN) and high Froude number (HFN), are simulated with a Serre–Green–Naghdi model, and the results are compared with the experiments by Treske (1994). We show that contrary to Favre waves and HFN bores, which are controlled by dispersive non-hydrostatic mechanisms, LFN bores correspond to a hydrostatic phenomenon. The dispersive-like properties of the LFN bores is related to wave refraction on the banks in a way similar to that of edge waves in the near shore. A fully hydrostatic asymptotic model for these dispersive-like bores is derived and compared to the observations, confirming our claim. [ABSTRACT FROM AUTHOR]

The reconstruction of water wave elevation from bottom pressure measurements is an important issue for coastal applications, but corresponds to a difficult mathematical problem. In this paper we present the derivation of a method which allows the elevation reconstruction of water waves in intermediate and shallow waters. From comparisons with numerical Euler solutions and wave-tank experiments we show that our nonlinear method provides much better results for the surface elevation reconstruction compared to the linear transfer function approach commonly used in coastal applications. More specifically, our method accurately reproduces the peaked and skewed shape of nonlinear wave fields. Therefore, it is particularly relevant for applications on extreme waves and wave-induced sediment transport. [ABSTRACT FROM AUTHOR]

The internal gravity waves and the turbulent wake of a sphere moving through stratified fluid were studied by the fluorescent dye technique. The Reynolds number Re=U·2a/v was kept nearly constant at about 3 · 10 and the Froude number F;U/a N ranged from 0.5 to 12.5. It is observed that waves generated by the body are dominant only when F<4 and are replaced by waves generated by the large scale coherent structures of the wake when F>4. [ABSTRACT FROM AUTHOR]

The far wake of a sphere towed horizontally in a linearly stratified fluid with Froude numbers F ∈ (0.25,12.7) and Reynolds numbers Re ∈ [150,30 000] is investigated. Regardless of the initial Froude number, the wake becomes quasi two dimensional at times large compared with the Brunt–Väisälä period. For F≤4.5, the horizontal motions are coherent over the whole depth of the wake. The wake takes the form of a regular von Kármán street for F≤1.5 but is irregular at larger F. For F≥4.5 the far wake consists of, vertically incoherent, horizontal motions in several layers. The transition occurs smoothly by a vertical decorrelation of the horizontal motion in the depth of the far which starts at F=4.5. The most novel result is that the horizontal velocity and vertical vorticity diffuse vertically in a time much shorter than predicted by a viscous diffusion law. The ratio of the observed diffusion time to the viscous diffusion time is expected to depend on Reynolds number as is indicated by a simple model. [ABSTRACT FROM AUTHOR]

In this paper experimental results on the near field of the flow past a sphere in a linearly stratified medium are presented. Emphasis is placed on the variation of the flow separation line with internal Froude number F=U/NR and also with Reynolds number Re=2RU/ν, where U and R are, respectively, the velocity and the radius of the sphere, N is the Brünt–Väisälä frequency (rad sec-1 ), and ν is the cinematic viscosity. It is shown that in the Reynolds number range 2001.5 the flow starts to recover its three-dimensionality. [ABSTRACT FROM AUTHOR]

Bruneau, N.; Bonneton, P.; Pedreros, R.; Dumas, F. and Idier, D., 2007. A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Acquitanian Coast, France. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 932 – 936. Gold Coast, Australia, ISSN 0749.0208 Along coasts, waves and wave-induced currents are the main factors of morphological evolution. A morphodynamic model is constructed to take into account tide changes, wind conditions and waves in the computation of the induced currents and morphological evolution. The spectral wave model SWAN, the shallow-water model MARS and a sedimentary module are coupled to create the morphodynamic model. First, we validate the hydrodynamics of the model on two characteristic complex bathymetries: an idealised subtidal crescentic bar and an intertidal ridge and runnel system. The crescentic bar induces wave energy focalisation zones which could give rise to transverse bars. Thus, we investigate the morphology evolution of the intertidal area. Simulations appear to show the formation of inner bars that connect the subtidal bar with the intertidal area. [ABSTRACT FROM AUTHOR]