Study On Characteristics Of Propagating Internal Solitary Wave Along Side Boundary And Its Force Imposed On A Submerged Slender Body

In this paper,the strait in ocean is simplified into a sinusoidal side boundary geometry structure.The numerical simulation method has been used to study the propagation of the internal solitary wave along the side boundary and its forces imposed on a submerged slender body.A seris of experiments have been carried out in a large-type stratified fluid tank,which supported the results from the numerical simulation.According to the characteristics of the force imposed on the submerged slender body by internal solitary waves,new working principle of the emergency lifesaving device for a submerged moving-vehicle is proposed to make up for the shortcomings of the traditional rescue method in the sudden sinking process.The obtained achievements can provide reference for the safety submarine aircraft sailing near the strait.The innovations and main conclusions of the paper are as follows:Firstly,the numerical method based on RNG k-? turbulence model is used to study the generation and evolution of the internal solitary wave along the side boundary and its forces imposed on a submerged slender body.In large stratified flow tanks,a model test system and analysis method for the non-stationary internal wave and its forces imposed on the structures are established.The exploring practices have been completed that the numerical simulation results are verified through the measurement and analysis in physical model tests.Secondly,the effective method of numerical simulation combined with the tank model test is used to objectively describe the evolution characteristics of the wave-flow field during the propagation of the internal solitary wave along the side boundary.In the side boundary contraction section,the position near the side boundary is hindered by the terrain,the small amplitude internal solitary wave waveform is vertically stretched and horizontally contracted,and the amplitude is increased,and the horizontal shear flow velocity of the upper and lower layers is reduced.Away from the side boundary,the amplitude is reduced but the shear flow rate is increased.the shear flow rate is the largest,because the cross-section of the central channel of the side boundary is the smallest.In the side boundary expansion section,the waveform is vertically contracted,horizontally stretched,the amplitude is reduced,and the shear flow rate is reduced compared to the central passage.For large internal isolated waves,the waveform appears to be distorted,broken and split.And the elliptical vortex structure in the typical solitary wave flow field is irregularly twisted,and a large number of vortices appear in the expansion section,which aggravates its energy dissipation.Thirdly,the numerical and physical model tests are used to reveal the characteristics of the force exerted by the internal solitary wave on the submerged slender body under the side boundary conditions.In the side boundary contraction section,the force suffered by the submerged slender body increases with the increase of the initial amplitude,and the closer the lateral distance from the side boundary is,the greater the horizontal,lateral and vertical forces are affected.In the side boundary expansion section,the force suffered by the submerged slender body increases first and then decreases with the increase of the initial amplitude.The farther the lateral distance from the side boundary is,the greater the effect of the vertical force and the lateral force.Horizontal forces are related to spatial position,density stratification ratio,and model parameters.Fourth,based on the characteristics of the internal solitary wave acting on the slender body,a working principle for the emergency rescue device is proposed when a submerged moving-vehicle falls in some dangerous situations such such as the internal wave.The feasibility of the device is verified by a real example.Compared with the traditional rescue means,the new device possess a lot of better characteristics such as small size,easy portability,simple operation,high reliability and so on.