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

• Published in: Ocean engineering 2024-05, Vol.299, p.117277, Article 117277
• Main Authors: Tsai, Ching-Piao, Ko, Chun-Han, Shih, Han-Chen, Chen, Yueh-Heng, Chen, Ying-Chi
• Format: Article
• Language: English
• Subjects: Bragg reflection; RANS equations; Submerged breakwaters; Wave breaking; Wave height transformation; Wave run-up
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2024.117277

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-ε 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. •Compares wave height at single high-crest vs. series of low-crest breakwaters.•Four breakwaters exhibit Bragg reflection, significantly reducing transmission height.•Single breakwater induces wave breaking, resulting in similar transmission height.•Under identical wave conditions, run-up on the rear slope is lower in single breakwater.•Practical configurations inducing wave breaking may enhance coastal protection.