Study of the overtopping flow impacts on multifunctional sea dikes in shallow foreshores with an hybrid numerical model

Corrado Altomare, Yuki Oshima, Xuexue Chen, Alejandro Crespo, Tomohiro Suzuki

Monday 29 june 2015

16:15 - 16:30h at Central America (level 0)

Themes: (T) Special session, (ST) Smoothed particle hydrodynamics and other meshfree methods

Parallel session: 3H. Special session: Smoothed Particle Hydrodynamics and other meshfree methods

The present work describes the validation of a hybridization technique between two different numerical models, namely SWASH and DualSPHysics, to study the impact of overtopping flows on multifunctional sea dikes in shallow foreshores. Previous works on the SWASH-DualSPHysics hybridization were presented by Dominguez et al. (2014) and Altomare et al. (2014), where the technique was validated against physical model results of wave propagation and run-up over sandy beaches. The present work aims to extend the use of this hybridized model to the analysis of wave-structure interaction: a typical case from the Belgian and Dutch coastline is used, where a building is constructed on the top of the dike. The building represents the last defense against the overtopping flows and the wave loads acting on it have to be properly characterized. Physical model tests were carried out at Flanders Hydraulics Research to measure forces on the vertical wall (i.e. building), the layer thickness and velocities of the overtopping flows. The results from the experimental campaign have been used to validate the hybridization. SWASH is previously validated against the physical model results: wave propagation, transformation and breaking have been accurately modelled and the conditions at the toe of the dike are reproduced as in the physical model test. Then SWASH is implemented together with DualSPHysics to model the wave impact. A hybridization point along the physical domain has been defined. SWASH provides the boundary conditions for DualSPHysics at that location. DualSPHysics is used to model the closest part of the domain to the dike. The results of this hybridization strategy confirm the accuracy of the technique. Water surface elevation, velocity field of the overtopping flows and wave forces, as measured in DualSPHysics, are in good agreement with the physical data. The results of the validation are reported in this work.