Numerical simulation of damping effect of ballast water system on motion response of immersed tunnel element

• Published in: Ocean engineering 2023-08, Vol.281, p.114795, Article 114795
• Main Authors: Wang, Sen, Xu, Tiao-Jian, Dong, Guo-Hai, Wang, Tong-Yan
• Format: Article
• Language: English
• Subjects: Ballast water sloshing; Immersed tunnel element; Regular waves; Rolling-damping
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2023.114795

The OpenFOAM was extended to analyze the roll motion of an immersed tunnel element excited by outside waves and inside ballast water sloshing. The reliability of our numerical model was validated by comparing the results with related experimental tests. Then, the effect of filling depths of ballast water on damping roll motion of a 2-D tunnel cross-section excited by regular waves was analyzed, and the effect of tank width with constant filling weight on rigid-fluid coupling was also discussed. Results revealed that a crucial filling depth for best damping performance on roll motion of liquid-carrying structures exists between the dry condition and the filling depth corresponding to the most severe resonance condition. For the application of the tunnel element in this study, a dimensionless filling depth of 0.1 shows the best damping effect. Furthermore, for different tank widths with a constant filling weight, the damping effect of the ballast water is mainly dominated by the natural frequency of ballast water and has a negative correlation with the natural frequency, for small natural frequency of large tank width, the phase lag between roll motion and sloshing moment gets closer to the maximum damping lag of π/2 due to violent sloshing flow. •An improved numerical model based on OpenFOAM for investigating the roll motion of a 2-D cross-section of immersed tunnel element excited by the regular waves and ballast water sloshing was developed.•This study is conducted based on the parameters of immersed tunnel element used in Hong Kong–Zhuhai–Macao Bridge (HZMB) in China.•The sloshing and wave forces are obtained to analyze their contribution to tunnel motion and for a beneficial analysis on the fluid-tunnel coupling mechanism.•The crucial filling depth in damping the maximum tunnel motion for different waves has been investigated in detail, and the effect of tank width with a constant filling weight on damping performance is also discussed.