Abstract
The interaction between an oceanic internal solitary wave (ISW) and a prototype submerged floating tunnel (SFT) is numerically investigated. Effect of oceanic internal solitary wave amplitude, the relative distance of the SFT to the pycnocline, cross-sectional geometry of the SFT, and the density ratio of the two fluid layers are analyzed. At a potential application site, the dynamic response of an SFT composed of a tube-joint-mooring system forced by an oceanic ISW is studied using Finite Element Method (FEM) modeling. The numerical results show that the ISW-induced force can be effectively reduced by adopting a parametric SFT cross section instead of a circle or ellipse. The influence of the relative distance of the SFT to the ISW pycnocline is crucial, and can remarkably alter the vertical force and buoyancy-weight ratio (BWR) of the SFT during ISW propagation. Large shear forces and bending moments on the SFT can occur, affecting the tension in the mooring lines, and threatening the safety and reliability of the SFT system. However, the deflections and accelerations of the SFT under the applied ISW are within structural serviceability requirements due to the low frequency of the ISW compared to the natural frequency of the SFT tube.
Highlights
Internal waves have been confirmed by satellite images and in situ observations as ubiquitous in oceanic environments (Vazquez et al, 2008), (Klymak et al, 2006)
To eliminate the scale effect, this present paper studies a full-scale prototype submerged floating tunnel (SFT) subjected to oceanic internal solitary wave (ISW)
As the flow passes over the SFT, the shear stress near the SFT surface grows, and the flow separates from the SFT due to the strong adverse pressure gradient (APG) resulting from the shape curvature, triggering a wide wake recirculation regime and periodic vortex shedding at the left edge
Summary
Internal waves have been confirmed by satellite images and in situ observations as ubiquitous in oceanic environments (Vazquez et al, 2008), (Klymak et al, 2006). ISW’s have been recorded with amplitude over 170 m (Klymak et al, 2006), and have been observed to penetrate the entire water depth These ISWs can induce large wave forcing and cause severe hazards to the operation and maintenance of marine engineering structures. Cui et al (2019) experimentally studied the motion and mooring force of a floating model under ISW impact, and found that the ISW amplitude and the model size are crucial factors affecting the structural response.
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