Laboratory measurement of oblique irregular wave reflection on rubble-mound breakwaters

The present work aims to improve our knowledge of reflection coefficient of waves on a breakwater through a programme of laboratory tests. The experiments are conducted on a linear rubble-mound breakwater under random long-crested wave conditions. The wave signals are recorded through an array of 8 wave probes. Three wave reflection analysis approaches are applied and compared on the laboratory recorded data: Least-Squares Methods, Directional Analysis Methods, Modified Directional Analysis Methods. These methods are briefly presented, their assumptions are highlighted and their characteristics are discussed on numerical tests. The Directional Analysis Methods appear to be unable to properly model the superimposition of incident and reflected wave fields. When applied to laboratory experiments, the Least-Squares Methods and the Modified Directional Methods show concordant results, but nevertheless exhibit some differences. The effect of oblique incidence on reflection coefficient is then tentatively analysed.