Hydrodynamic optimization and performance verification of fairings for round-ended cofferdams using dam-break wave experiments and numerical simulations

• Published in: Applied ocean research Vol. 153; p. 104247
• Main Authors: Xu, Guoji, Jiang, Zexing, Zhou, Jiaguo, Xu, Lele, Liao, Zhengbowen, Xu, Yong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2024
• Subjects: Dam-break wave; Hydrodynamic characteristic; Load reduction; Round-ended cofferdam; Shape optimization; Hydrodynamic characteristic; Load reduction; Round-ended cofferdam; Shape optimization; Dam-break wave
• ISSN: 0141-1187
• DOI: 10.1016/j.apor.2024.104247

•A novel auxiliary fairing is proposed for super-large round-ended cofferdam.•This novel fairing can effectively reduce the drag and lift coefficients.•An adaptive surrogate model is utilized for hydrodynamic optimization of the fairing.•Performance of the optimized fairing is further verified in dam-break wave experiments. Round-ended cofferdams are crucial for large-scale marine projects but are vulnerable to the complex marine environment, including waves, tides, and storms. Enhancing the hydrodynamic performance of these cofferdams is essential for improving safety and efficiency in marine construction. This study introduces a novel fairing design aimed at reducing water flow resistance during the quasi-stable stage of a tsunami. The flow field is analyzed using computational fluid dynamics (CFD) simulations, and an adaptive surrogate model is employed to optimize the parameterized fairing shape. The results demonstrate that the optimized shape significantly suppresses vortex shedding, leading to a 16.59 % reduction in the drag coefficient and a 44.3 % reduction in the lift coefficient under flow conditions. Experimental and numerical simulations of dam-break waves are conducted for two designs, R1 and R0. By comparing their flow field and force characteristics, it is found that R1 effectively separates waves during the impulse stage, reduces wave climb height, and decreases impact loads. In the quasi-stable stage, R1 mitigates the blockage effect, reducing the liquid level difference between the front and back, and thus lowering flow forces. Experimental data further reveals that when the downstream is a dry riverbed, R1′s load reduction is particularly notable, with maximum reductions of 45.62 % in the impulse stage and 28.75 % in the quasi-stable stage. When the riverbed is wet, the maximum load reduction rates are 18.04 % and 8.72 %, respectively. Therefore, R1 not only reduces the resistance of round-end cofferdams under water currents but also under extreme wave forces, providing valuable insights for advancing ocean engineering design.