Numerical study of wave overtopping on sea-dikes with crown-walls

• Wave overtopping on sea-dikes with crown-walls is examined experimentally and numerically using NLSWE and RANS models.
• Owing to wall schematizations NLSWE model is robust and sufficiently reliable for estimate of overtopping rates.
• RANS model reliably predicts overtopping rates and green depths, but seriously under-estimate splash heights.
• Wall influence is not simply an added freeboard but more about efficiency in dissipating wave run-up momentum.
• Seadikes with promenades are more effective in dissipating wave energy and better improve splashing conditions.

Models based on non-linear shallow water (NLSW) and Reynolds-Averaged Navier Stokes (RANS) equations are applied to investigate the characteristics of wave overtopping on sea-dikes with low vertical crown-walls. Wave overtopping experiments of both regular and irregular waves were carried out to validate the models. Thanks to pragmatic wall schematization approaches a simple NLSW model can effectively be applied to predict the right wave overtopping discharges for cases of relatively low walls. The process of the wave–wall interaction is both experimentally and numerically examined using a RANS model, which gives more insight into the wall influence on wave overtopping. Also, the RANS model is found to reliably predict average wave overtopping discharges and maximum green overtopping depths, whilst seriously under-estimate maximum splash heights.