Wave overtopping of non-conventional rubble-mound breakwaters: Blind comparison between experimental and numerical data

Modifying existing harbor breakwaters to adapt to new environmental conditions requires addressing technical and economic challenges. Physical and numerical modeling play a crucial role throughout these design stages, especially when dealing with non-conventional structures. However, synthesizing the results from independent experimental and numerical studies can be challenging. In this context, the objective of the present work is to contribute to the development of practical guidelines for the engineers involved in the complex design of non-conventional harbor breakwaters. To this aim, here a blind comparison between experimental and numerical data on wave overtopping for upgraded rubble-mound breakwaters is presented. Both experimental and numerical mean overtopping discharges align well with predictions by EurOtop (2018), and the variability of the combined dataset is comparable to the internal variability within the numerical data. The numerical model demonstrates a strong ability to reliably estimate mean wave overtopping discharge, performing similarly to specifically calibrated models reported in the existing literature. However, significant discrepancies are observed between experimental and numerical time series of individual wave overtopping volumes, which are likely due to differences in wave generation methods and measurement techniques, as well as scale effects and limitations inherent in numerical modeling. Given these findings, numerical modeling of wave overtopping in non-conventional rubble-mound breakwaters proves to be a powerful tool for design phases requiring mean discharge estimation. However, for applications that necessitate precise modeling of individual overtopping volumes, specially calibrated models are recommended to enhance accuracy.