Numerical Study Of The Evolution Of Internal Solitary Waves And Their Interactions With Submerged Bodies

The internal solitary wave is a large-scale dynamic phenomenon that exists in the ocean.Its existence poses a serious threat to ocean engineering structures.Therefore,the internal solitary wave has become an environmental factor that must be considered in ocean engineering design.With the development of marine resources going into deep sea,it is of great practical significance to study the generation and evolution of the internal solitary wave and its interaction with ocean engineering structures.On the basis of summarizing former research,numerical simulations are conducted to study the evolution of the internal solitary wave over the terrain and its interaction with the submerged body.The main research contents are as follows:The commercial computational fluid dynamics software Fluent is redeveloped by using the user-defined function.The velocity inlet method is used to implant the horizontal velocity of a two-layer fluid in the internal solitary wave theory model into the inlet boundary.By this means,a numerical internal solitary wave tank for a two-layer fluid system which realizes the generation and stable propagation of the real scale internal solitary wave is established.Based on this numerical wave tank,numerical simulations of propagations of real scale internal solitary waves over simplified guyots are carried out.Variations of wave parameters and flow field when internal solitary waves of different amplitudes pass through terrains with different heights are analysed.The results show that waveform,wave amplitude and wave energy,as well as horizontal velocities of the upper and lower layers of the fluid,vorticity and turbulent kinetic energy of fluid around the terrain change significantly.As the height of the terrain and the amplitude of the internal solitary wave increase,the degree of interactions between the internal solitary wave and the terrain strengthens,and the degree of changes of the physical quantities mentioned above increases.Based on this numerical wave tank,numerical simulations of interactions between real scale internal solitary waves and submerged bodies are also carried out,and loads acting on submerged bodies when internal solitary waves of different amplitudes pass through submerged bodies with different depths are analysed.The results show that submerged bodies are subjected to huge loads under the action of internal solitary waves.When the depth of the submerged body is fixed,loads acting on it increases with the increase of the wave amplitude.When the amplitude of the internal solitary wave is constant and submerged bodies are in the same layer of the fluid,loads acting on them increase with the decrease of the distance between submerged bodies and the interface of two layers,but the variation value is small.When the amplitude of the internal solitary wave is constant,loads acting on the submerged body in the upper layer is greater than that in the lower layer,and the ratio between these two loads is consistent with the ratio of horizontal velocities of the upper and lower layers.