Graduation of Martijn van Heest

Numerical estimation of the upward pressure difference over a placed block revetment under wave loading on a dike

• Professor of graduation: Prof. dr. ir. M.R.A. van Gent

• Supervisors: Dr. ir. R.J. Labeur (TU Delft), Ir. M. Horstman (Royal HaskoningDHV)

To improve the design process of a placed block revetment and reduce the number of required physical flume tests, computational fluid dynamics (CFD) can be used. The aim of this thesis was to determine whether CFD modelling is able to accurately predict the uplift of the top layer of a placed block revetment and to identify the optimal approach for modelling this type of revetment. In order to reach this goal, a CFD model is created and validated with a physical test performed in the Delta Flume. The model performance has been evaluated on three consecutive processes. First, the wave generation and propagation are analysed by comparing the wave spectra of the incoming wave heights and monitoring the wave height and period during propagation towards the structure. The model was able to reproduce a similar wave spectrum and the wave properties remained constant during propagation. The second process that has been evaluated is the wave-breaking process that results in wave loads on the slope. It has been shown that the quasi-static wave loads are predicted with reasonable accuracy (i.e. measured values deviate less than 10%) while the dynamic wave loads deviate up to 35% from the physical test results. It is concluded that there is room for improvement in modelling the wave-breaking process. The last evaluated process is the internal flow that leads to pressure differences over the top layer. The predicted upward pressure differences have a deviation of less than 20%. The model has demonstrated its ability to capture underlying mechanisms governing wave-structure interaction. The CFD model can mostly be of value by providing more qualitative insights into wave structure interaction for placed block revetments.