Wave overtopping pressures and spatial distribution behind rubble mound breakwaters

Currently, there is no widely accepted method to determine the pressure profiles induced by wave overtopping behind the crest of a breakwater other than physical modelling. In this experimental study, the spatial distribution of overtopping pressures on a vertical structure is investigated at various distances behind a rubble mound breakwater with a crown wall. A 2D physical modelling study in presented in an attempt to derive a practical method for estimating these overtopping pressures. The variability of overtopping wave pressures behind the crest of a breakwater is also discussed. Rule of thumb guidelines are proposed which will contribute to better concept and schematic structural designs in advance of physical model testing

Modelling of wave and currents around submerged breakwaters

Recent experimental data collected during the DELOS project are used to validate two approaches for simulating waves and currents in the vicinity of submerged breakwaters. The first approach is a phase-averaged method in which a wave model is used to simulate wave transformation and calculate radiation stresses, while a flow model (2-dimensional depth averaged or quasi-3D) is used to calculate the resulting wave driven currents. The second approach is a phase resolving method in which a high order 2DH-Boussinesq-type model is used to calculate the waves and flow. The models predict wave heights that are comparable to measurements if the wave breaking sub-model is properly tuned for dissipation over the submerged breakwater. It is shown that the simulated flow pattern using both approaches is qualitatively similar to that observed in the experiments. Furthermore, the phase-resolving model shows good agreement between measured and simulated instantaneous surface elevations in wave flume tests

Final phase-resolving Boussinesq-type models (D42)

The design of structures to be built in the nearshore region generally involves the evaluation of different possible layouts, under the effects of local wave and cunents conditions, with the aim of minimizing costs and maximizing the desired results. In particular the design of lowcrested structures involves optimisation of several parameters, which influence both the position, and the shape of the structures. The possible layout of the structures to be designed can be tested experimentally in wave tanks and wave flumes using adequate scale models. An alternative and attractive procedure is to employ suitable numerical and mathematical models. In principle, a very advanced numerical model, able to conectly simulate all the nearshore phenomena (turbulence, waves, currents, sediment transport, etc.) could be equivalent or even superior to a physical model. In practice, the numerical models currently employed in engineering activities, use several assumptions and simplifications: the phenomena that can be simulated strictly depend on the governing equations solved by the model. Indeed, the great advantage of numerical and mathematica! models is that their application is usually much less expensive than physical ones: it is certainly more economie to modify a computer file describing the bathymetry of the area under investigation than rebuild a physical model layout. This report is structured into two discrete sections, the first one contributed by AUTh and the second one by UR3. In the first section a 2DH higher-order Boussinesq-type model combined with a porous flow model, developed tor simulating flow around porous submerged structures is presented. On the other hand, in the second section enhancements on the applicability of Boussinesq-type equations (BTE) into the surf and swash zone are described.Delo