A finite volume method based Cartesian grids is adopted to solve the Navier-Stokes equations using Improved Delayed Detached Eddy Simulation turbulence model with OpenFOAM for the study the 3D evolution as a large depression internal solitary wave propagates across a vertical cylinder. Numerical results reveal that these significant differences of density and kinematic pressure are found at both sides of the cylinder and the complex vortex is occurred around the cylinder because of partially transmission and reflection effect. Moreover, the kinematic pressure difference may maintain a maximum as the radius is over the critical value in the same physical condition.


Internal solitary waves (ISWs) exist in a density stratified flow and are usually generated by the tide-topography interaction, especially in South China Sea (SCS) (Alford et al., 2015). Due to its large amplitudes up to 170m and strong velocity difference exceeding 2.4 ms-1 between its upper and lower water layer (Chang et al., 2008), an ISW has significant ramification not only in marine ecology but also engineering works in the ocean (Bourgault et al., 2014; Lamb, 2014; Wang et al., 2007). Reports (Lamb, 2014; Reeder et al., 2008) also concludes that (1) self-generation of the vortices with strong turbulent mixing within the water column and (2) waveform inversion across a continental shelf are two of the highlights of an ISW across a slope-shelf topography.

As an ISW propagates around large vertical cylinders (i.e., an Island), wave diffraction can be observed significantly in some previous studies (Lynett and Liu, 2002; Tang et al., 2015). For small vertical cylinders, such as deep-sea oil drilling rigs or pipelines, the strong velocity difference induced by an ISW propagation causes the threat to these structures (Cai et al., 2008; Song et al., 2011; Xie et al., 2011). The interaction between surface wave and small cylinder has been vigorously studied in several decades, however, the investigations about discussing that between an ISW and the obstacle has less references, especially at small cylinder. Although some researchers (Cai et al., 2008; Song et al., 2011; Xie et al., 2011) used numerical simulation to discuss the responses between ISWs and the small vertical cylinder, they almost simplified the problem and did not discuss the turbulent effect. In order to further study the 3D interaction between a depression ISW and small vertical cylinder, a series of numerical modeling about a depression ISW propagating across a small vertical cylinder are employed and revealed in this paper.

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