Wave transport past slotted barriers

• Main Author: Ong, Mei Ling.
• Other Authors: Lo Yat-Man, Edmond
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/15855
• Institution: Nanyang Technological University

To assess the influence of oceanic waves on coastal areas, coastal engineers have done significant research and analysis of wave behaviour and coastal structure performance. Past researches have placed strong focus on behaviour of regular waves and on typical breakwaters such as caisson and rubble-mound types. In this report, the effects of solitary waves on slotted breakwaters will be investigated due to the need to come up with more extensive information on the above-mentioned areas. This is achieved through model experiments and later on, further analyses. Different gap-to-barrier width ratios produce varying effectiveness of the slotted barrier in dissipating incident wave energy. For this project, different barrier gap widths are explored in the quest of determining the best gap-to-barrier width ratio. The ratios discussed are 0.25, 0.375, 0.5 and 0.625. In the laboratory experiments, water depth in the flume is varied (10 cm, 15 cm, 20 cm and 25 cm) and for each water depth, three different solitary wave heights are generated (5 cm, 7 cm, 10 cm). The magnitude of incident and transmitted wave heights are measured and logged and the results are plotted against Hi /d (incoming wave height over water depth), from which the transmission coefficient and energy transmission ratio are calculated. The effects of wave height and barrier geometry on the transmission coefficients are examined. The analysis also includes calculation of the energy dissipation efficiency. The experimental results showed that all gap-to-barrier ratios were able to dissipate varying amounts of energy; in particular the ratio of 0.375 appears to be the best ratio for reduction of wave height attenuation and dissipation of energy as compared to the other selected ratios. Some limitations pertaining to laboratory modeling were discussed and recommendations to overcome said limitations were made at the end of the paper with due considerations to feasibility of application.