Numerical investigations of gap resonance excited by focused transient wave groups. (15th September 2020)

• Record Type: Journal Article
• Authors: Gao, Junliang; Chen, Hongzhou; Zang, Jun; Chen, Lifen; Wang, Gang; Zhu, Yazhou
• Is Part Of: Ocean engineering. Volume 212(2020)
• Publication Date: 2020-09-15
• Subjects: Gap resonance -- Focused transient wave group -- Wave height amplification -- Wave forces -- Response time and damping time -- OpenFOAM®; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2020.107628
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Two or more structures arranged side by side with narrow gaps may be suffered from large-amplitude free-surface oscillations, which could cause green water on the deck and lead to dramatic increase of hydrodynamic loading acting on structures. Here, transient resonant motions of the free surface inside a narrow gap between two fixed boxes triggered by focused transient wave groups with various focused wave amplitudes are simulated using a two-dimensional numerical wave tank. The free-surface amplifications not only inside the gap but in the vicinity of the two-box system, the response time and the damping time of the transient gap resonance, the maximum wave loads on both boxes and the relative importance of the higher-order wave loads to the first-order ones are systematically investigated. It is found that the most vulnerable position to green water closely depends on the incident focused wave amplitude. The damping time decreases gradually with increasing focused wave amplitude, while the response time seems insensitive to the latter. As the focused wave amplitude increases, the normalized maximum wave loads on both boxes are also shown to decline gradually overall, while the relative importance of the higher-order wave loads to the first-order ones becomes more and more remarkable. Highlights: Transient gap resonance between two fixed boxes triggered by focused wave groups is simulated by using OpenFOAM® model. Four different hydrodynamic characteristics involved in the transient gap resonance are comprehensively investigated. The hydrodynamic characteristics studied include: (1) the free-surface amplifications inside the gap and in the vicinity of the two-box system, (2) the response/damping time, (3) the maximum wave loads and (4) the relative importance of the higher-order wave loads to the first-order ones. All these hydrodynamic characteristics of transient gap resonance depend closely on the incident focused wave amplitude except the response time.