The influence of a berm and a vertical wall above swl on the reduction of wave overtopping

The Eurotop Manual, based on the TAW guidelines, recognizes the reducing effect of a vertical wall or a berm on wave overtopping over an impermeable slope. Nevertheless, these reduction factors are only introduced in the formula for breaking waves. Furthermore, the berms for which reduction factors are proposed are mainly located below the SWL. In this paper, the reducing effect of a berm above SWL, a vertical wall and the combination of both are investigated. Reduction factors have been deducted, and are introduced in the existing overtopping formulae for an impermeable slope

Coastal flooding risk calculations for the Belgian coast

Coastal flooding risk calculations are carried out for the entire Belgian coastal zone to support the management ofthe coastal defence system. The floodprone low-lying coastal area has an average width of 20 km and is locatedon average 2 m below the surge level of an annual storm. The natural sea defences are sandy beaches anddunes, which have been strengthened by revetments in the coastal towns. The Belgian standard of coastalprotection is to be safe against a surge level with a return period of 1000 years, but at present it is investigated if and how this standard could be redefined based on risk analysis

UPDATE OF THE EUROTOP MANUAL: NEW INSIGHTS ON WAVE OVERTOPPING

Quite some new insights on wave overtopping were achieved since the first submission of the EurOtop Manual in 2007, which have now resulted in a second edition of this Manual. A major improvement has been made on the understanding of wave by wave overtopping and tolerable wave overtopping that is connected to it. Many videos are available on the overtopping website that show all kind of overtopping discharges and volumes and may give guidance for the user of the Manual. The EurOtop Neural Network and the EurOtop database are improved and extended versions of the earlier NN and CLASH database. New insights and prediction formulae have been developed for very low freeboards; for very steep slopes up to vertical walls; for run-up on steep slopes; for overtopping on storm walls on a promenade; and for overtopping on vertical walls, where overtopping has been divided in situations with and without an influencing foreshore and where the first situation may be divided in non-impulsive and impulsive overtopping

Interactions of breaking waves with a current over cut cells

By design of the external and internal wave–current generators, the objective of this paper is to extend our efficient Navier–Stokes solver [T. Li, P. Troch, J. De Rouck, Wave overtopping over a sea dike, J. Comput. Phys. 198 (2004) 686–726] for modelling of interactions between breaking waves and a current over a cut-cell grid, based on a dynamic subgrid-scale (SGS) model. This solver is constructed by a novel VOF finite volume approach, coupled with surface tension. When studying waves following a positive current, our external generator creates the combined inflow motions of waves and a current, which is viewed as one type of wavy inflow conditions. For cases of waves against strong currents, our internal generator describes the opposing current, by incorporating the source function to the continuity and momentum equations as a net driving force, acting on the fluid elements lying within the finite thickness source region. The outgoing waves downstream are dissipated with a breaking-type wave absorber placed in the tank extremity. Five test cases recommended are of distinctly different applications of interest, characterized by overtopping of following waves over sloping and vertical structures.Under the grid refinement effects, the results in 2D and 3D are in close agreement with the experimental data available in terms of the surface wave. Additionally, the performance of convergence in computations is also investigated, including full discussion for waves on beaches between 2D and 3D. By visualization of the motions that describe the physics of turbulence, it has been shown that our solver can capture most of the significant features in wave–current interactions varying with three different current speeds (positive, zero, negative)

Two-piece implants with turned versus microtextured collars.

Item does not contain fulltextImplant companies have been promoting two-piece implants with microtextured collars in the interest of hard tissue preservation and/or soft tissue integration. However, this rationale may not be justified. Based on comparative studies currently available, it is unclear whether microroughened implant necks reduce crestal bone loss. A possible effect may be overruled by the establishment of a biologic width or by other factors influencing crestal bone remodeling. In addition, the orientation and attachment of the collagen fibers in the peri-implant mucosa are a little different because the surface roughness varies at the level of the implant neck. The clinician should be cautious when using these modified implants because the impact of microtextured collars on the initiation and progression of peri-implant pathology is currently unknown