Study On The Interaction Between Internal Solitary Waves And The Submerged Body

The strong nonlinear internal solitary wave in the interior of the ocean produces shearing action to the submerged body across the thermocline,which seriously affects the safety of the submerged body.In this paper,a numerical method based on commercial software ANSYS15.0 in a two-layer fluid is presented to simulate the interaction of internal solitary waves with a submerged body,where the velocity-inlet boundary is calculated by the three types of internal solitary waves theories including KdV,eKdV and mKdV.Firstly,a comprehensive review of the state of the art of the research area is taken.Then the analysis of load and responses of the interaction between internal solitary wave and the submerged body in the ocean is performed.The main research work and achievements are as follows:(1)Three kinds of internal solitary wave theory are introduced briefly.And make a system introduction about related knowledge of CFD numerical simulation,such as numerical method,simulation method and dynamic mesh technology,etc.(2)Based on three internal solitary wave theories and the volume of fluid method,the 2D and 3D numerical internal solitary wave tank are established by controlling the velocity of velocity-inlet The numerical results are compared with theoretical and experimental ones to verify the feasibility of this wave-generating scheme.And the flow field characteristics of internal solitary waves are analyzed.(3)With the feasible internal solitary wave numerical tank,the load of internal solitary waves acting on a submerged body is investigated.The regular pattern of the horizontal force,vertical force and moment of the submerged body under internal solitary wave is calculated and analyzed.The variation of the load is related to the location of the submerged body,the amplitudes of the internal solitary waves,the upper and lower depth and the type of the internal solitary wave.Finally,the variation of wave surface and surface pressure of the submerged body by two types of internal solitary waves are analyzed.(4)By the use of dynamic mesh,the motion response of the submerged body under the influence of internal solitary waves is numerical simulated.Three-DOF motion response of three locations of the submerged body and the relationship between the trajectory of the submerged body and the flow field of the internal solitary waves are analyzed.And its force situation is compared with the fixed case.The results show that the submerged body will produce very large surge motion in the upper fluid,the drift in the horizontal and vertical direction will be disastrous when it closes to the wave surface,the submerged body can reduce the influence of the internal solitary wave when it leaves away from the wave surface.The trajectory of the submerged body is the same as that of the velocity field induced by the internal solitary wave,similar to a half ellipse.In addition,the influences of the amplitudes of the internal solitary waves,the upper and lower depth and the type of the internal solitary wave on the motion characteristics of the submerged body are analyzed.The results show that the internal solitary waves have a great influence on the safety of the submerged body in actual sea conditions.Submerged body should be rational planning its operating area in order to reduce the losses caused by internal solitary waves.