M.R.A. van Gent

The modelling of wave action on and in coastal structures

Description of the wave action on and in coastal structures can lead to a prediction of flow properties and forces on elements of those structures. For permeable structures several aspects concerning the interaction between the external flow and the internal flow have to be described accurately to predict for instance velocities and run-up levels. The P.C.-model ODIFLOCS, developed at Delft University of Technology within the framework of the European MAST-Coastal Structures project, describes the wave motion on and in several types of structures. This structure can be an impermeable or a permeable structure. For instance dikes, breakwaters and submerged structures can be dealt with. The model is a one-dimensional model based on long wave equations. The program takes various phenomena into account such as reflection, permeability, infiltration, seepage, overtopping, varying roughness along the slope, linear and non-linear porous friction (Darcy- and turbulent friction), added mass, internal set-up and the disconnection of the free surface and the phreatic surface. Satisfactory results were obtained with modelling of run-up, surface elevations and velocities. Other applications show more possibilities of the model.

NUMERICAL SIMULATION AND VALIDATION OF PLUNGING BREAKERS USING A 2D NAVIER-STOKES MODEL

A special reflecting wall 12 m long and 2.1 m high was built off the beach at Reggio Calabria, and 30 wave gauges were assembled before the wall and were connected to an electronic station on land. It was possible to observe the reflection of wind waves generated by a very stable wind over a fetch of 10 Km. The experiment aimed to verify the general closed solution for the wave group mechanics (Boccotti, 1988, 1989), for the special case of the wave reflection.Significant features on Wadden Sea wave climate are evaluated in respect of the state of the art. Main emphasis was laid on an analysis of the governing boundary conditions of local wave climate in island sheltered Wadden Sea areas with extensions being sufficient for local wind wave growth. Explanatory for significant wave heights a reliable parametrization of local wave climate has been evaluated by using generally available data of water level and wind measurements.

WAVE ACTION ON AND IN PERMEABLE STRUCTURES

A special reflecting wall 12 m long and 2.1 m high was built off the beach at Reggio Calabria, and 30 wave gauges were assembled before the wall and were connected to an electronic station on land. It was possible to observe the reflection of wind waves generated by a very stable wind over a fetch of 10 Km. The experiment aimed to verify the general closed solution for the wave group mechanics (Boccotti, 1988, 1989), for the special case of the wave reflection.Significant features on Wadden Sea wave climate are evaluated in respect of the state of the art. Main emphasis was laid on an analysis of the governing boundary conditions of local wave climate in island sheltered Wadden Sea areas with extensions being sufficient for local wind wave growth. Explanatory for significant wave heights a reliable parametrization of local wave climate has been evaluated by using generally available data of water level and wind measurements.