Comparative study of wave height transformation: Bragg reflection versus wave breaking at submerged rectangular breakwaters

This study investigates wave height transformation caused by either a single high-crest or a series of low-crest submerged rectangular breakwaters through laboratory experiments and numerical simulations. The series configuration induces Bragg reflection without wave breaking, while the single breakwater leads to wave breaking. Numerical models, employing two-dimensional RANS equations coupled with the k-epsilon turbulence model, are validated against experimental data. The analysis encompasses wave height transformations, wave reflection and transmission coefficients, and the flow field linked to different breakwater arrangements. Results indicate that the four-breakwater series prominently demonstrates Bragg reflection, resulting in reduced transmission wave height. Conversely, the single high-crest submerged breakwater induces wave breaking, dissipating more turbulence energy and yielding a similar transmission wave height. Additionally, the wave run-up height on the rear slope behind breakwaters is lower in the single breakwater scenario under identical incident wave conditions.